Category Archives: Claims-based Authentication

MFA Conditional Access Policies in AD FS 2012 R2

October 23, 2014AD FS R2, Claims-based Authentication, Multi-Factor Authentication, Web Application Proxy, Windows Server 2012 R2AD FS R2, Claims-based Authentication, MFA, Multi-Factor Authentication, Windows Server 2012 R2mylo

Hello again. The previous Multi-Factor Authentication (MFA) post on User Certificates provided an opportunity to expand and look at some of the more interesting scenarios for MFA conditional access. This “interest”, if I may call it that, stemmed from playing around with MFA over the last few months and looking at the role of conditional access polices therein.

Ramiro Calderon wrote a great article on MFA policy here and it comes highly recommended. As he mentions in his post, the AD FS claims engine computes MFA authentication requests (defined via the AD Management UI) in a logical OR fashion. This can be initially a little confusing and we’ll take a look at some more creative use of MFA policies, to handle more flexible access scenarios in R2.

MFA Primer

To make use of MFA, an MFA provider is required. In a vanilla AD FS R2 setup, this is limited to certificate authentication using client certificates (see previous post). For other MFA options, check with your favorite 2FA vendor to see if they’ve written an MFA adapter for AD FS R2.

In the global authentication policy, the MFA provider needs to be enabled.

Let’s have a look at what happens when MFA is enabled through the AD FS Management UI. MFA policies can be triggered either globally (applicable to all relying parties), or on the relying party itself.

In the example below, MFA is required for securing access to applications outside of the organization, what Microsoft call Extranet use.

Users connecting from outside the corporate network will be prompted after successful AD username/password authentication by the MFA handler.

When the MFA policy is set globally, this can be seen in PowerShell via the Get-AdfsAdditionalAuthenticationRule

c:[Type == "http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork", Value == "false"] => issue(Type = "http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod", Value = "http://schema s.microsoft.com/claims/multipleauthn");

If a global authentication policy is not specified, but the policy is enabled in a relying party rule, then an additional authentication rule, defined on the RP, is evaluated. This allows for a more refined use of policy and I’ll show examples of this, by way of scenarios, later in the post.

The AD FS Management UI is sufficient for applying the use of MFA in most single “context” access scenarios. By this I mean, we are able to enforce the requirement of MFA to satisfy policies, that stipulate additional authentication is required by use of one of either user/group, device or location. For example, if we determine that a MFA policy needs to be used by location only, e.g. Extranet, we simply select the Extranet location checkbox. All users connecting from outside of the corporate network must then use MFA. Conversely, if we want to enforce MFA for a specific subset of users/groups, irrespective of their location (Extranet/Intranet), by adding them via the users/groups option in the UI, this can be also be set. Finally, we can also specify that unregistered or registered devices (a la Workplace Join) need to use MFA, via the devices checkboxes. The fact that these policies may also be applied independently on a per relying party basis, often satisfy basic access policy needs.

The challenge arises when dealing with a combination of policy, for example, when stating an MFA requirement by device and by location.

AD FS will now trigger MFA when an unregistered device (non-workplace joined) connects to AD FS AND also when users are connecting from the Internet The policies are evaluated independently and we may unwittingly be enforcing MFA for a registered device in a Workplace Join scenario, when the desired outcome was actually to ensure that a single authentication factor (the device certificate paired with the user concerned) was sufficient for access from the outside. This is the logical OR behavior that Ramiro refers to in his post.

Similar behavior can be observed if the following settings are made.

Here we have a specific user/group requiring MFA and also the location (Extranet) checkbox is checked. Users who are members of the GU-SEC-ADFS-MFA group must always use MFA, irrespective of their location AND other users, connecting from outside of the corporate network, will be challenged by the MFA handler. Again, if the intention was to enforce MFA for a combination of outcomes; namely, by group and location outside, then this is not the outcome.

Rules are evaluated independently when set via the UI. Given that requirements via the UI operate this way, if there is a requirement to enforce MFA via policy where:

it’s an unregistered device AND
connecting from the Internet

OR in the second example where:

user is member of group X AND
connecting from the Internet

The AD FS Management UI doesn’t support this arrangement. Instead, more refined policies can be handled with PowerShell, using combinations of authentication rules. As with the UI, this can be expressed either as a global authentication policy applicable to all relying parties (Set-AdfsAdditionalAuthenticationRule) or MFA policies defined on a per relying party basis (Set-AdfsRelyingPartyTrust). I’ll use the latter to drum up examples of setting finer-grained access rules in the scenarios that follow. More work for us admins, but greater flexibility to boot…

Scenario A: Externally connecting workplace joined device (registered user)

Requirement: Registered users on Workplace Join devices connecting from outside the corporate Internet may authenticate using the device authentication certificate. All other users/devices must use MFA.

$rp = Get-AdfsRelyingPartyTrust –Name "WIF Test Application"
Set-AdfsRelyingPartyTrust –TargetRelyingParty $rp –AdditionalAuthenticationRules ‘c: [Type == "http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork", Value == "false"] && [Type == "http://schemas.microsoft.com/2012/01/devicecontext/claims/isregistereduser", Value == "false"] => issue(Type = "http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod", Value = "http://schemas.microsoft.com/claims/multipleauthn");’

Scenario B: MFA for External Access by Security Group

Requirement: Users who are members of Group X, when connecting from outside the corporate network, must use MFA.

$rp = Get-AdfsRelyingPartyTrust –Name "WIF Test Application"
Set-AdfsRelyingPartyTrust –TargetRelyingParty $rp –AdditionalAuthenticationRules ‘c: [Type == "http://schemas.microsoft.com/ws/2008/06/identity/claims/groupsid", Value == "S-1-5-21-Insert your Group SID here"] && [Type == "http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork", Value == "false"] => issue(Type = "http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod", Value = "http://schemas.microsoft.com/claims/multipleauthn");’

Scenario C: MFA Security Group Exception for External Access

Requirement: Users who are members of Group X are exempt from a general policy stipulating use of MFA when connecting from the outside of the network. All other users must use MFA. Note: We flip the behavior with the Group SID claim use in Scenario B by using the NOT EXISTS evaluation.

$rp = Get-AdfsRelyingPartyTrust –Name "WIF Test Application"
Set-AdfsRelyingPartyTrust –TargetRelyingParty $rp –AdditionalAuthenticationRules ‘exists([Type == "http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork", Value == "false"]) && NOT EXISTS ([Type == "http://schemas.microsoft.com/ws/2008/06/identity/claims/groupsid", Value == "S-1-5-21-Insert your Group SID here"]) => issue(Type = "http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod", Value = "http://schemas.microsoft.com/claims/multipleauthn");’

Scenario D: MFA using a custom evaluation rule

Requirement: The Azure Sprout organization is using “vanity” UPNs to enforce MFA for non-standard UPN suffixes. Corporate users with an @azuresprout.com UPN suffix may use single factor (forms) authentication from the outside. All other UPN suffixes in the “organization” must use MFA.

$rp = Get-AdfsRelyingPartyTrust –Name "WIF Test Application"
Set-AdfsRelyingPartyTrust –TargetRelyingParty $rp –AdditionalAuthenticationRules ‘NOT EXISTS([Type == "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn", Value =~ "^.*@azuresprout\.net$"]) => issue(Type = "http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod", Value = "http://schemas.microsoft.com/claims/multipleauthn");’

Scenario E: MFA based on custom claims extrapolated from an attribute store

Requirement: An SQL attribute store is used to augment claims when accessing a business application. Values extracted from the store are to be used as triggers for MFA.

On the relying party, we connect to an attribute store and populate an sqlrole claim, based on running a stored procedure to find the user and the appropriate access information for user on application FOO.

c:[Type == "http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname"%5D => add(store = "SQL Attribute Store", types = ("http://schemas.microsoft.com/ws/2008/06/identity/claims/sqlrole"), query = "EXEC dbo.GET_ACCESSTOKEN @UserID={0},@AppCode=’FOO’", param = c.Value);

Next, on the RP pipeline, we define the MFA requirement based on value returned in the sqlrole claim .

$rp = Get-AdfsRelyingPartyTrust –Name "WIF Test Application"
Set-AdfsRelyingPartyTrust –TargetRelyingParty $rp –AdditionalAuthenticationRules ‘c:[Type == http://schemas.microsoft.com/ws/2008/06/identity/claims/sqlrole”, Value =~ "<Whatever the response we’re expecting for MFA trigger>"]) => issue(Type = "http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod", Value = "http://schemas.microsoft.com/claims/multipleauthn");’

The latter scenario is a little more unusual, but I’ve used it to highlight what is possible (as with Scenario D) outside of the normal conventions provided by the UI.

As a sneak peek into the new Window Server “10” release, it appears that Microsoft have expanded authentication support and making the nuances of policy-based access control more accessible to the end user, through the use of a new policy template editor, made available to the AD FS administrator.. more on this and another ADFS “stuff” to come…

Here’s a snippet of the new rules editor from the pre-release.

MFA with Client Certificates in ADFS 2012 R2

May 27, 2014AD FS R2, Claims-based Authentication, MFA, Multi-Factor Authentication, Relying Party, Strong Authentication, Web Application Proxy, Windows Server 2012 R2AD FS R2, Client Certificates, MFA, Multi-Factor Authentication, Web Application Proxy, Windows Server 2012 R2, Workplace Join, X509mylo

There have been questions on this subject posted recently to comments and also on the TechNet forums, so I just wanted to quickly write up something about use of client certificates in the MFA (secondary) slot in AD FS 2012 R2. You may recall from earlier AD FS R2 posts, that we used virtual smart card and smart card as examples. Let’s broaden that to include “soft” client certificates as an MFA/secondary provider. This functionality is provided “out-of-the box” in AD FS 2012 R2. An Active Directory Certificate Services (AD CS) infrastructure is required to serve up certificates for enabling users for PKI.

In this post, I’ll be using an Active Directory Certificate Services (AD CS) role from Windows Server 2012 R2 as the Certification Authority (CA). I won’t be explaining the CA setup, beyond the templates used, as there’s been plenty of ink expended on this topic already on the Internet. A Windows 2003/2008/2012 CA setup will suffice for the activities concerned here.

Testing was done with client certificates from a Windows 8.1 clients using:

a non domain-joined machine, via Certificate Enrollment (Policy) Web Services and Microsoft Management Console (MMC)
a domain-joined machines, via an auto-enrollment policy User-Context GPO.

In AD Certificate Services (AD CS) a duplicate of the default User certificate template was made (called User V2). Under the Application Policy, the policy is limited to Client Authentication.

For domain-joined clients, we can enable auto-enrollment via the security tab of the template. Here we see a group called GU-SEC-ADCS-Managed, which is given the necessary read, enroll and autoenroll permissions and we can add users to that security group.

To enable auto-enrollment for domain-joined clients we need to activate a policy to accomplish this. Against best practices (boo), but for expediency (mine.. yay!), I enable the policy in the Default Domain Policy GPO. The actual settings can be find under Windows Settings|Security Settings|Public Key Policies. Select the Certificate Services Client – Auto Enrollment object and enable the Configuration model section as seen below.

For the non-domain joined client, read and enroll permissions are given to a group I’ve called GU-SEC-ADCS-Workgroup. The test user, who will be a member of that group, can request the UserV2 certificate template via the Certificates|User MMC plug-in using AD CS Certificate Enrollment Web Services. Again, I won’t be describing how to setup enrollment web services. If you need help, just post in the comments section.

With Certificate Services, we need to make available the template available to both sets of clients, by enabling the template in the Certification Authority MMC plugin – Certificate Templates|New|Certificate Template to Issue.

In a correctly configured setup, domain-joined clients will obtain a certificate on the next GPO refresh cycle for the user (e.g. logon).

As mentioned previously, I’m joining non-domain joined clients via enrollment web services using the MMC snap-in in Windows 8. In the Certificates|User context of the MMC snap-in, we request a new certificate. In this particular test setup, there are three certificate templates visible for enrollment by the client from the CA:

User V2 is the template we just created for use for “soft” client certificates.The certificate services enrollment point in this example is configured for Username/Password authentication. Logon is done with a test AD user account training@azuresprout.net, who is a member of the GU-SEC-ADCS-Workgroup and authorized with the enroll permission.

Once that’s done, a client certificate is installed in the user context.

On the AD FS side of things, let’s assume we now need to apply MFA for users (with client certificates) coming from the Internet. Before we jump into the actual AD FS settings, it’s worth mentioning that any firewalls in front of the Web Application Proxy (WAP) will need to allow port 49443/TCP inbound, as this is the port the AD FS Smartcard Authentication Service listens on.

We see evidence of this requirement in the Windows Firewall snap-in. AD FS creates a firewall rule during the installation allowing 49443/TCP inbound.

In AD FS Global Authentication Policy for MFA, we enable certificate authentication:

Note that at this point, I’m not enforcing the use of MFA globally, rather enabling it for use at a lower level on a relying party rule, for more incremental control. Whether to go for global or granular policies really boils down to a question of fit and the use cases may need to support. .

On a test Windows Identity Foundation (WIF) relying party, MFA is enforced for externally connecting users.

Logging on to the relying party, we hit the primary authentication handler (AD FS forms), enter our username/password.

Connecting from the Internet, with MFA enabled, the secondary (MFA) authentication handler kicks in and we’re presented with a login popup.

In the above graphic, we have an option to login with a virtual smart card (top) and an X509 client certificate (bottom). Click on the certificate and AD FS will authenticate the user using secondary authentication (MFA).

The enrolled certificate is stored by AD CS in the userCertificate attribute of the user object within AD. This attribute contains the DER-encoded X509v3 certificates issued to the user. We can lookup the necessary certificate reference, for example, in the Attribute Editor of AD Users & Computers (ADUC).

This is a multi-valued attribute.

One thing that can be useful, should you be working with multiple certificates for a given user, is being able to cut and paste the hex encoded value into Notepad, save it, then check to see what the certificate value corresponds to using CERTUTIL.

certutil –decodehex mylo.hex mylo.cer

We can then open the .cer file to see what the certificate is.

Returning to the test claims applications (having logged in successfully0, we pass all claims processed via an issuance transform rule of c:[] => issue(claim = c);
We can see the relevant authentication method references processed during primary and secondary logon.

As I mentioned in an earlier post, the nice thing here is that you can use the Enhanced Key Usage (EKU) claim emitted for both client certificates and smart cards / virtual smartcards to moderate access to resources as you see fit.

Looking at a user authenticating with a client certificate, the following EKU is emitted as a claim.

Smart cards also emit the smart card EKU

Access can also be further graded by using custom OIDs to differentiate between levels of access based on the type of MFA being used and the EKU value.

Use of certificates in the MFA slot in R2 (I suspect) are really geared for use in a true two-factor (2FA) authentication capability, i.e. smart cards. While the use of a client certificate does offer value in offering richer access possibilities, this is not 2FA, in that it does not satisfy the mantra of “something I have and something I know”. Instead, this is more akin to 1.5FA.

To finish up, Microsoft recently added support in Windows 7 for domain-joined clients via a hotfix. I’ll attempt to throw out a quick post on this, but in the meantime, I’ll be following up by looking at conditional access policies for MFA.

As always, thanks for reading and if you have any questions, please post a comment and I’ll do my best to answer quickly.

Exchange 2013 SP1, Outlook Web App (OWA) and AD FS

March 13, 2014AD FS R2, Claims-based Authentication, Exchange Control Panel, Exchange Server 2013, Outlook Web App, Web Application ProxyAD FS 3.0, AD FS R2, ADFS, ECP, Exchange 2013 SP1, OWAmylo

It’s over a year now since the last Outlook Web App article about integrating OWA with ADFS. In that post we explored the use of claims-based authentication with OWA in a Proof of Concept using WIF 3.5 and FedUtil. This was an unsupported setup in Microsoft eyes and, in the meantime, with the release of Windows Server 2012 R2, opportunities for supporting Exchange web applications such as OWA, have arisen. The first, provided support via the use of a non-claims aware web application in AD FS R2 using Kerberos Constrained Delegation (KCD), utilizing the new Web Application Proxy (WAP) feature. The recent release of Exchange 2013 SP1 further expands OWA support, including native support for AD FS in the Exchange product, with claims-based authentication now possible for Outlook Web App (OWA) and the Exchange Admin Center (EAC).

To get started, I’ll refer you to a Technet article here that provides a step-by-step. I used this article as a starting point for setting up OWA/EAC with AD FS R2. These two application endpoints in Exchange (OWA and ECP) need to be represented as relying parties within AD FS.

Here’s an excerpt of the PowerShell rules required for creating the RPs:

Add-ADFSRelyingPartyTrust -Name “Outlook Web App” -Enabled $true -Notes “This is a trust for https://mail.mydomain.com/owa” -WSFedEndpoint https://mail.mydomain.com/owa -Identifier https://mail.mydomain.com/owa -IssuanceTransformRules $IssuanceTransformRules -IssuanceAuthorizationRules $IssuanceAuthorizationRules

Add-ADFSRelyingPartyTrust -Name “Exchange Admin Center (EAC)” -Enabled $true -Notes “This is a trust for https://mail.mydomain.com/ecp” -WSFedEndpoint https://mail.mydomain.com/ecp -Identifier https://mail.mydomain.com/ecp -IssuanceTransformRules $IssuanceTransformRules -IssuanceAuthorizationRules $IssuanceAuthorizationRules

The AD User and Group SIDs, together with UPN also need to be defined for each of the Exchange Relying Party applications in the form of custom claims rules: Windows Account Name (sAMAccountName)

c:[Type == “http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname”, Issuer == “AD AUTHORITY”] => issue(store = “Active Directory”, types = (“http://schemas.microsoft.com/ws/2008/06/identity/claims/primarysid”), query = “;objectSID;{0}”, param = c.Value);

Group SID (enumarate group membership)

c:[Type == “http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname”, Issuer == “AD AUTHORITY”] => issue(store = “Active Directory”, types = (“http://schemas.microsoft.com/ws/2008/06/identity/claims/groupsid”), query = “;tokenGroups(SID);{0}”, param = c.Value);

User Principal Name (UPN)

c:[Type == “http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname”, Issuer == “AD AUTHORITY”] => issue(store = “Active Directory”, types = (“http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn”), query = “;userPrincipalName;{0}”, param = c.Value);

On the Exchange side, via PowerShell, we specify the Relying Party Identifiers via the AdfsAudienceUris parameter and must also provide the token signing certificate thumbprint from the AD FS server.

$uris = @(“https://mail.mydomain.com/owa”,”https://mail.mydomain.com/ecp”) Set-OrganizationConfig -AdfsIssuer “https://adfs.contoso.com/adfs/ls/” -AdfsAudienceUris $uris -AdfsSignCertificateThumbprint “TOKEN SIGNING CERTIFICATE THUMBPRINT”

Don’t forget to import the token signing certificate into the Trusted Root Certificate Authorities container of your Exchange servers, otherwise you may fall foul of the following error logging on to your mailbox.

The source in pinpointing the problem here, lies in the query string of the error message https://external.mydomain.com/owa/auth/errorfe.aspx?msg=WrongAudienceUriOrBadSigningCert.

In this (my) case, the token signing certificate had not been added to the Exchange servers as a trusted cert. Equally, the wrong Audience URI can present a configuration problem. It commonly arises when a unnecessary trailing slash is added to the Relying Party Identifier when configuring in AD FS, e.g. https://mail.mydomain.com/owa/. s something to keep an eye on. The correct RP identifier would be https://mail.mydomain.com/owa.

I’ve not yet tested setting up Exchange 2013 SP1 under AD FS 2.0, but there’s nothing untoward going on here to suggest that using it as your identity provider is not possible. If you’re running under AD FS Windows Server 2012 R2 then the Web Application Proxy (WAP) adopts the proxy role for external access scenarios and also supports host name translation. For example, I make use of https://external.mydomain.com as an external URL and map this to the internal name of https://mail.mydomain.com. Be aware that matching of path-based names is not supported in the current release of the WAP, so mixing path names between externally and internally published resources is a no-no.

To illustrate this, let’s look at an example of an OK configuration:

Add-WebApplicationProxyApplication -BackendServerUrl ‘https://mail.mydomain.com/owa/’ -ExternalCertificateThumbprint ‘DD94E2ABAA123C6B6009CB42F16CE892AF96A47C’ -ExternalUrl ‘https://external.mydomain.com/owa/’ -Name ‘OWA’ -ExternalPreAuthentication ADFS -ADFSRelyingPartyName ‘Outlook Web App’

Whereas, this is a non-workable configuration.

Add-WebApplicationProxyApplication -BackendServerUrl ‘https://mail.mydomain.com/owa/’ -ExternalCertificateThumbprint ‘DD94E2ABAA123C6B6009CB42F16CE892AF96A47C’ -ExternalUrl ‘https://external.mydomain.com/mail/’ -Name ‘OWA’ -ExternalPreAuthentication ADFS -ADFSRelyingPartyName ‘Outlook Web App’

Note the use in publishing of the same literal path https://external.mydomain.com/owa/ in the first example, versus a rewritten one in the second https://external.mydomain.com/mail/.

If you’re contemplating the use of AD FS 2.0, then clearly host-name translation is not something that the AD FS 2.0 proxy brings to the table. Alternatively, a suitably equipped front-end load balancer may also fulfill that role.

On the subject of load balancers, this rather conveniently brings me back to new features in AD FS R2. Server Name Indication (SNI) was mentioned in the “First Looks” articles about AD FS R2 and it’s worth checking that your current load balancer/reverse proxy in front of AD FS supports SNI and is supported/enabled on the device concerned. This is becoming a pain point for many, as evidenced by various posts on the Technet forums. The move to kernel-mode (HTTP.SYS) in R2 mandates the use of SNI. Therefore, it’s worthwhile checking that:

your friendly neighbourhood load balancer/device in front of AD FS supports SNI
clients and user agents support SNI and you’re not inadvertently locking them out
(08/04) SSL termination endpoints (e.g. load balancer / 3rd-party reverse proxies) in front of AD FS may be affected by the recent heartbleed bug (http://heartbleed.com), exposing vulnerable OpenSSL libraries and certificates used on those devices. Microsoft infrastructure, employing Secure Channel (SChannel) not affected, may inadvertently become so through SSL termination endpoints on the aforementioned devices in front of AD FS. More information can also be found here (http://www.kb.cert.org/vuls/id/720951)

Accessing the OWA URL, via https://external.mydomain.com/owa and the OWA Relying Party redirects the user to AD FS for logon. In a default AD FS R2 configuration, this equates to forms-based authentication for external users.

Users accessing OWA internally, access https://mail.mydomain.com via the farm using Integrated Windows Authentication (IWA). As usual when connecting to the farm, the URL for the federation service needs to be added to the Local Intranet Zone within IE and any corresponding configuration changes made to support Kerberos for other browsers.

At this point, optional use of a clams provider (connecting to the local AD) or an MFA provider in R2 could also come into play to provide stronger authentication, should it be required. Having successfully authenticated via AD FS, we gain access to the user mailbox.

The Exchange Control Panel (ECP) was also configured as a relying party within AD FS and within the Exchange configuration. Accessing the Exchange Admin Center remotely, with the Exchange Organization Administrator mylo, we can see the gamut of administrative console options available under federated logon.

This is one of those scenarios where it might be a good idea to apply stronger authentication (MFA) to privileged user accounts when accessing the Exchange Admin Center. We can do this by applying policy-based access on the AD FS R2 server.

In the next post, I’ll be taking a look at strong authentication access scenarios using ActiveSync and Lync (primarily with mobile clients), before completing Part 3 of the First Looks series of AD FS R2.

First Impressions – AD FS and Window Server 2012 R2 – Part II

January 7, 2014AD FS 2.2, Claims-based Authentication, Home Realm Discovery, MFA, Window Server 2012mylo

Hi folks. Welcome back to Part II of our first look at the new AD FS release in Windows Server 2012 R2. This one has been a while in the making and for those who have been waiting, thanks for your patience. This is a pretty long post and the longest to date. For the most part it emphasises what is new and good in the Windows Server 2012 R2 incarnation of AD FS, in particular concentrating on the authentication and UI changes in the latest release.

In the last post we looked at some of the new architectural changes in AD FS with Windows Server 2012 R2, such as the Web Application Proxy, Extranet soft lockout and a lightweight domain join facility, otherwise known as Workplace Join. In this post we’ll extend the look to some of the authentication/UI changes and how their application embraces a more conditional access approach and philosophy within the product.

In AD FS 2.0, customization of IIS and sign-in pages could be performed on both the AD FS Proxy and AD FS farm with authentication types being used configured in the web.config file of each.

The AD FS 2.0 proxy supported the following authentication types:

Username and Password (Forms)
X509/Client Certificate (including Virtual Smart Card/Smart Card Authentication)
Basic Authentication

The AD FS 2.0 backend (farm) supported the following authentication types.

Integrated Windows Authentication (IWA)
Username and Password (Forms)
X509/Client Certificate (including Virtual Smart Card/Smart Card Authentication)
Basic Authentication

Authentication mechanisms carried over from AD FS 2.0 are now available under the banner of Primary Authentication in R2 and handled through the AD FS Management UI or via PowerShell. As with AD FS 2.0, native authentication assumes the use of an Active Directory-based identity and the built-in AD claims provider for authentication. Support for Basic Authentication, available in AD FS 2.0, has now been deprecated in R2.

Looking at the AD FS Management UI, we see an immediate difference over its predecessor with the inclusion of a new authentication policies pane.

In AD FS 2.0 the base proxy and farm configuration supported Forms and IWA logon types respectively. Any changes beyond that required adjusting the LocalAuthenticationTypes
methods used within web.config
files on proxy and farm nodes. The context-sensitive (proxy v farm) aspects of authentication now move to the UI/PowerShell. There is also support for multiple authentication types for a given authentication context, such as simultaneous support both Forms and X509 Certificate-based authentication on the external context handler.

Within the Management UI we may edit the Global Authentication Policy on the AD FS server to determine what authentication types we wish to support on the Primary authentication space and for internal/external user types.

These settings can also be modified via PowerShell. For example, the following command sets forms-based logon as the authentication type for both Extranet and Intranet logons on Primary Authentication.

Set-AdfsGlobalAuthenticationPolicy -PrimaryExtranetAuthenticationProvider {FormsAuthentication} -PrimaryIntranetAuthenticationProvider {FormsAuthentication}

An additional authentication provider, in the form of Multi-Factor Authentication (MFA), allows support for additional (stronger) authentication types. This auxiliary component represents a significant enhancement for sign-in scenarios under AD FS in Windows Server 2012 R2.

Under the previous release, native support for stronger authentication was limited to domain-joined clients using Smart Cards or Virtual Smart Cards, via the X509/Client certificate authentication handler. Third-party solutions materialised providing support for two-factor/multi-factor authentication in the federation logon process. How these were implemented varied per solution, but they typically fell into one of two basic categories:

Agent-based or non-federated solutions (typically) running on, or in front of the AD FS proxy, handling two-factor authentication (2FA) for external access.
Claims/Identity Providers trusted by AD FS.

If you’ve followed this blog over time or from own experience, you’ll know these approaches can have their own quirks: be they issues with cross-domain SSO, redirection, home realm discovery, flexibility, user experience etc., they often warranted some attention configuration-wise to get working under AD FS 2.0, where possible.

The R2 makeover overcomes some of these limitations by:

Expanding access capability within AD FS, making available more fine-grained “conditional access” decisions;
Improving login behaviour and user experience for sign-in scenarios;
Improving customization of sign-in pages / error-handling;
Including the option of a secondary MFA adapter (SDK) for vendors to integrate with, unifying the logon experience around AD FS itself.

Let’s have a look at more conventional access scenarios, using AD FS 2.0 as a reference point. We begin by seeing how the new authentication changes enhance options during logon. In AD FS 2.0, while we were able to change the preferred authentication type, supporting multiple authentication options was not possible without significant customization. An example is provided here for reference.

Customizing User Agent Behaviour

Under AD FS 2.0 Integration Windows Authentication (IWA) provided transparent SSO to domain-joined Windows clients connecting web resources that supported Windows authentication. However, IWA is not supported by all browsers and under AD FS 2.0 the fall-back authentication was NTLM.

The NTLM challenge/response dialogue often caused confusion for users. With AD FS in Windows Server 2012 R2, we can specify on the internal network which browser clients are allowed to use Integrated Windows Authentication (IWA) for transparent logon. This is done by modifying the supported user agents via the following cmdlet.

Set-ADFSProperties –WIASupportedUserAgents

Internal clients, using Internet Explorer 6.0 and above will default to using their Windows logon token (IWA) when connecting from the Intranet. All other browser agents, Firefox, Chrome etc. will revert to using forms-based authentication (FBA). If the user agent in question is added to a WIASupportedUserAgents list then IWA is attempted. This gives the IT Administrator greater control, whilst promoting a more user-friendly logon experience.

We can customize our own User Agent values to pass to AD FS. I had to dig around to work out how to set this value correctly because it’s not obvious what the settings in AD FS are at first glance. If we type Get-ADFS Properties, we can see some of the current user agent settings, with the remaining values beyond MSIE 8.0, being obscured from view.

The viewing properties are being limited by a setting known as $FormatEnumerationLimit in PowerShell. When we change the value of this to -1 we see the full user agent specification used.

$FormatEnumerationLimit=-1

We can then change the supported user agents by using the Set-ADFSProperties
cmdlet. I actually broke things at this point and my ignorance of PowerShell was to blame. As posters to Technet forums confirmed, the following syntax will not work:

Set-AdfsProperties -WIASupportedUserAgents (“MSIE 6.0”, “MSIE 7.0”, “MSIE 8.0”, “MSIE 9.0”, “MSIE 10.0”, “Trident/7.0”, “MSIPC”, “Windows Rights Management Client”)

It turns out that a string array is required and the user agent items need be in parenthesis and an @ included. Thank you PowerShell Pro. Reverting to the original configuration is possible by setting the following command and you can, of course, customize accordingly.

Set-ADFSProperties -WIASupportedUserAgents @(“MSIE 6.0”, “MSIE 7.0”, “MSIE 8.0”, “MSIE 9.0”, “MSIE 10.0”, “Trident/7.0”, “MSIPC”, “Windows Rights Management Client”)

If you’re propagating your own IE settings, e.g. via GPO, then these can be added to the list. If you’re using other browsers, besides IE, then it’s also worth considering turning off Extended Protection Authentication (EPA) / Channel Binding Token (CBT). This can be done via the following command:

Set-ADFSProperties –ExtendedProtectionTokenCheck None

Note the service restart request. Please note that EPA is intended as a protection mechanism against Man-in-the-Middle (MITM) attacks and as ever it’s a toss-up between usability and security. An overview can be found here.

Authentication Changes

Let’s look at an example of multiple local authentication types enabled. Here, Forms and X509/certificate authentication are enabled on the primary authentication provider for external (Extranet) access at the Web Application Proxy (WAP):

In a logon scenario, with both options enabled, the user is presented with the following logon screen:

The option to “Sign in using an X.509 certificate” is provided underneath the logon form. Logging on with username/password to a test claims aware web application, we see the normal forms logon behaviour as seen with the AD FS 2.0 Proxy, expressed through the use of the PasswordProtectedTransport value in the authnmethodsreferences
claim.

With multiple authentication types enabled, users can logon using the forms logon option or using an X509 mechanism, e.g. a client certificate or virtual smart card/smart card.

I’m using a Virtual Smart Card (VSC) as an example for the X509 access type. Clicking on the X509 hyperlink, using the VSC we see the following prompt.

I select the VSC for user mylo.

At the challenge prompt, the user must enter their PIN for that user, whereupon they gain access to the relying party.

Looking at the claims emitted at this point through our test relying party, we can see that AD FS recognizes that stronger authentication has been used (MFA) and via the http://schemas.microsoft.com/claims/authnmethodsreference claim, it issues the value of http://schemas.microsoft.com/claims/multipleauthn. More on this in a moment.

Multi-Factor Authentication (MFA) on the Secondary Provider

The previous example illustrated the use of both username/password and MFA through the Primary Authentication option. When we look at Multi-Factor Authentication (MFA) via an additional authentication policy rule, we can similarly use the native X509/Certificate Authentication provider. This implies the use of the AD username/password first as the primary credential, either via forms or IWA, according to your authentication policy rules, and X509 as the additional MFA credential.

There’s a distinction here also worth noting between AD FS 2.0 and R2 behaviour. With the former we could potentially invoke multi-factor authentication (MFA) through protocol mechanisms, such as via a wauth parameter in WS-Federation, or in the AuthnContextClassRef in SAML 2.0. In doing so we were able to call an upstream identity provider that was MFA capable, or if stronger authentication mechanisms were available on AD FS 2.0, using X509 certificates or smartcard variants. The options here, at this point though were fairly limited and called on extensive customization to support multiple authentication methods.

We can still use the protocol route in AD FS R2. In addition, Multi-factor authentication (MFA) can be triggered through both protocol and policy (new in R2) rules. For example, with WS-Federation the wauth=http://schemas.microsoft.com/claims/multipleauthn protocol parameter stipulates that the relying party requires invocation of MFA in the logon request (assuming this is enabled in the global authentication settings). This is the same claim type mentioned earlier during the smart-card logon process and is associated with the use of MFA.

When we invoke MFA as a policy rule on the AD FS R2 server, we’re in fact calling the additional authentication rules handler and this policy-based behaviour can be configured at both global and relying party levels.

In the UI, we can see the following options:

The use of conditional access rules provide a more controlled demeanour to AD FS in how claims-based authentication is applied. In this example, I’ll disable Certificate Authentication in the primary authentication slot (leaving forms enabled) and enable it instead as an MFA method globally. We can then call on this (secondary) authentication method as we see fit.

The equivalent PowerShell command is:

Set-AdfsGlobalAuthenticationPolicy –AdditionalAuthenticationProvider CertificateAuthentication

For this particular test, I’ll also enabled MFA as a requirement for external clients

When logging on to AD FS R2, we get the standard forms sign-in page. We now using two-step authentication using the primary and the additional (secondary) authentication types.

Logging on with a username and password, we’re then presented with an additional logon screen and a request to provide secondary (X509) MFA credentials.

Again using a Virtual Smart Card( VSC) and our mylo test user, we select the appropriate VSC identity and enter a PIN.

Looking at a test claims-aware Windows Identity Foundation (WIF) application, passing through all claims rules, we see the following detail:

The aggregation of authentication types used during the logon process can be seen through the use of the
http://schema.microsoft.com/claims/authnmethodreferences
claim. The first claims value seen in the screenshot is for urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport, indicating use of forms logon (username/password). The second and third references to tlsclient and x509 show that we’ve used a client certificate (in the form of the virtual smart card) during the logon phase. Finally, the last entry states that multi-factor authentication (MFA) has been used, reflected in the http://schemas\.microsoft\.com/claims/multipleauthn claim value. A similar claim value would also have been emitted if we’d used a third-party authentication provider registered as an R2 MFA provider. We’ll look at this later in the post.

When we log on with a Virtual Smart Card (VSC), we can also see the Enhanced Key Usage (EKU) of a certificate emitted in the claim.

Those of a PKI inclination will appreciate the benefits this may provide. We are able now, for example, to determine, via the EKU, whether a smart card was used in the logon process (1.3.6.1.4.1.311.20.2.2), as opposed to say a vanilla client certificate and we can stipulate that as an access requirement during logon. If your organization is using a custom organizational identifier (OID) then we may also consider moderating access based on different levels of assurance associated with the OID bound to a particular certificate template. This also offers some promising developments with technologies such as Authentication Mechanism Assurance (AMA), which I’ll cover in a future post.

The examples I use with smart cards are typically targeted at managed Windows (domain-joined) clients, who receive their configuration (certificates etc.) over the (local) wire through group policy (GPO) or scripts. Support for non-domain joined clients, however, is now also available to Windows 8.1 clients and enrolment can now be provided via certificate enrolment/policy web services.

For a more granular approach to MFA, desired authentication can also be targeted to specific relying parties. The conditions under which we apply the policy rules (AD group/user, location, device, authentication type) can be refined on per relying party basis, as seen in greater detail in the next section with the MFA Adapter.

The MFA Adapter

This is a new feature in AD FS R2 that allows third-parties to register their authentication provider as an auxiliary authentication mechanism within AD FS, whilst unifying the login/sign-in experience around AD FS.

To see how the MFA adapter works, the example user here is with Windows Azure Multi-Factor Authentication Server, formerly PhoneFactor. A tenant has been setup in Windows Azure, a pre-requisite, with the Azure MFA server plugging into the Azure cloud and the registered tenant. The MFA Server itself connects to AD FS through an installer that provides the necessary bridge between the AD FS MFA adapter/SDK and the Azure MFA Server.

I’ll skim over the details of installing the actual Windows Azure Multi-Factor Authentication server itself and look at integration of the AD FS plug-in.

The Windows Azure MFA server connects to the local organization Active Directory and synchronizes objects with it. Here we’re synchronizing objects under an OU subtree of Accounts/External in the imaginary “Azure Sprout” organization. A single container subtree is being synchronized.

Looking at the User section of the console we see some test users in an organization called “Azure Sprout”.

We’ll enable the training user for phone-call validation.

Within the authentication server console, there’s an AD FS section where the appropriate adapter can be installed.

If the MFA server is joined to the domain and the Active Directory configuration for securing communication between the ADFS Adapter and the Multi-Factor Authentication service is incomplete, the administrator must first complete the Active Directory integration setup, before the adapter can be installed. Once the adapter is installed, the desired multi-factor authentication methods can be then specified.

In the testing example here, the AD FS adapter has been installed on the Federation Server and via the console, the necessary AD FS integration binaries installed. This can also be done manually, such as when the server is installed on a remote machine. The AD FS binaries can be copied through the C:\Program Files\Multi-Factor Authentication Server path and installed via an MSI (MultiFactorAuthenticationAdfsAdapterSetup64.msi). When run the installer sets ups the necessary resource files and connectors allowing AD FS to communicate with the on-premise WZAA MFA instance.

A PowerShell script then needs to be run to register the Windows Azure MFA adapter within the local AD FS instance and make it available as an MFA option.

With the Windows Azure Authentication Server installed and the MFA adapter registered, a new authentication type becomes available, which we can then enable in the Global Authentication Policy for the organization.

The adapter is now available as an MFA authentication method. The Multi-Factor Authentication Server itself is bound to a Multi-Factor Authentication Service setup on my Windows Azure tenant.

Let’s have a look at some test scenarios using MFA.

In the above test setup are two AD FS instances, both on R2, representing two different organizations: “Access Onion” and an Azure-based setup called “Azure Sprout”. The “Access Onion” organization is hosting a couple of on-site SharePoint web applications. Apologies if the setup looks a little bit contrived, but I’m not at the stage yet where I’m prepared to fork out $$$ for moving certain “demo/test” resources such as SharePoint/SQL to the cloud, hence the dual on-premise and cloud combination J

Two SharePoint web applications have been setup as relying parties to test some MFA scenarios:

A Teamsite dedicated to “Azure Sprout” users resides in the “Access Onion” organization. For expediency, I’ve connected up the SharePoint Teamsite (teams.azuresprout.net) directly to the AD FS in the “Azure Sprout” organization to test direct trust access scenarios. The SharePoint teamsite (teams.azuresprout.net) in the “Access Onion” organization is setup as a Relying Party on the “Azure Sprout” AD FS instance.
A Teamsite for users in the “Access Onion” organization that also provides secure access to users from the “Azure Spout” organization. For “Azure Sprout” users accessing the SharePoint Teamsite, they are routed via the “Access Onion” AD FS instance, acting in the role of a Relying Party Security Token Service (RP-STS). A claims provider trust is setup between the trusting (Resource) “Access Onion” organization and the trusted (Account) “Azure Sprout” organization, with the AD FS RP-STS setup as a Relying Party in the “Azure Sprout” organization AD FS instance.

For testing, please note that:

Users in the “Azure Sprout” have a @azuresprout.net
domain suffix
Users in the “Access Onion” have a @accessonion.net
domain suffix.

We’ll look at various access scenarios that employ new functionality within the R2 release of AD FS and begin with the “Azure Sprout” Teamsite dedicated for that organizations use.

Scenario 1 : Access to the “Azure Sprout” Teamsite

This is a fairly straightforward setup. This Teamsite is only for “Azure Sprout” users and there’s a direct trust between the SharePoint web application, hosted in the “Access Onion” organization and the “Azure Sprout” AD FS organization. This setup is analogous (for this test) to that of a normal Web SSO setup. We wish to use local Windows authentication for “Azure Sprout” internal users and MFA for external users connecting through the “Azure Sprout” Web Application Proxy (WAP).

The AD FS R2 instance for the “Access Onion” organization is omitted from the diagram as its role is secondary, with the Web Application Proxy being used as a reverse proxy for publishing the SharePoint application.

Internal Users

Represented in the diagram by blue numbering, users connected to the “Azure Sprout” Intranet can connect using their Windows credentials.

The User accesses the “Azure Sprout” Teamsite within the “Access Onion” organization. This is published by the local Web Application Proxy as a Reverse Proxy rule. The SharePoint Security Token Service (STS) has been configured to use the “Azure Sprout” AD FS as a trusted claims provider.
The user is redirected to the “Azure Sprout” AD FS instance. Since the user is connected to the Azure Sprout LAN, this passes the request directly to the farm instance, whereby the user can logon with their Windows credentials. A relying party rule is configured for the SharePoint Teamsite and claims rules (Send LDAP Attributes as Claims Rules) configured to pass the requisite attributes.

c:[Type == “http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname”, Issuer == “AD AUTHORITY”] => issue(store = “Active Directory”, types = (“http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn”, “http://schemas.microsoft.com/ws/2008/06/identity/claims/role”, “http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress”), query = “;userPrincipalName,tokenGroups,mail;{0}”, param = c.Value);
The user is redirect to SharePoint whereupon (assuming permissions have been granted to the SharePoint site) they gain access.

Here’s the identity provider configuration used for the “Azure Sprout” teamsite.

$map = New-SPClaimTypeMapping -IncomingClaimType “http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress” -IncomingClaimTypeDisplayName “EmailAddress” -SameAsIncoming

$map2 = New-SPClaimTypeMapping -IncomingClaimType “http://schemas.microsoft.com/ws/2008/06/identity/claims/role” -IncomingClaimTypeDisplayName “Role” -SameAsIncoming

$realm = “urn:azuresprout:teams”

$ap = New-SPTrustedIdentityTokenIssuer -Name “Azure Sprout” -Description “Azure Sprout SAML” -realm $realm -ImportTrustCertificate $cert -ClaimsMappings $map,$map2 -SignInUrl “https://sts.azuresprout.net/adfs/ls” -IdentifierClaim http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress

External Users

Represented in the diagram by black numbering, the logon workflow works as follows:

The User accesses the “Azure Sprout” Teamsite within the “Access Onion” organization. This is published by the local Web Application Proxy as a Reverse Proxy rule. The SharePoint Security Token Service (STS) has been configured to use the “Azure Sprout” AD FS as a trusted claims (identity) provider.
The user is redirected to the “Azure Sprout” AD FS instance. Since the logon request is coming from an external user, the request is resolved via external DNS, pointing to the “Azure Sprout” Web Application Proxy. A pre-authentication rule is configured for the SharePoint relying party on the web application proxy.

Add-WebApplicationProxyApplication -BackendServerUrl ‘https://teams.azuresprout.net/’ -ExternalCertificateThumbprint ‘D9433C468CDEDF6BCD645BC2DE143CD5B4ED108’ -ExternalUrl ‘https://teams.azuresprout.net/’ -Name ‘”Azure Sprout” Teamsites’ -ExternalPreAuthentication ADFS -ADFSRelyingPartyName ‘SharePoint “Azure Sprout” Teamsites’

External Users need to use MFA. We configure this on the “Azure Sprout” AD FS farm by specifying the appropriate location/MFA combination on the authentication policy for the SharePoint Relying Party.

Within the UI:

Looking at this in PowerShell, this translates to an additional authentication claim rule of:

c:[Type == “http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork”, Value == “false”]=> issue(Type = “http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod”, Value = “http://schemas.microsoft.com/claims/multipleauthn”);

In other words, if the user is inside the “Azure Sprout” corporate network, then the MFA rule will not apply because the insidecorporatenetwork claim value returns a value of $true). The use of the http://schemas.microsoft.com/claims/multipleauthn claim value is then used to trigger MFA as part of the rule above.

As discussed earlier the primary authentication type needs to be satisfied first. The user must log on with their “Azure Sprout” AD credentials. From the outside, the forms login handler is initiated for the (primary) initial logon type for external (Extranet) users.
Once the user has logged on with primary authentication, they must then logon with MFA. This is where the Windows Azure Authentication Server (MFA) provider comes into play. The user authenticates using their configured MFA type.

In the test configuration, the setup is configured to allow the Windows Azure MFA server to ring the users phone to complete authentication. Once they click on the Continue button the call is initiated, based on the number derived from the mobile attribute of the user in the “Azure Sprout’ Active Directory (the AD attribute used can be customized). The user confirms the two-step authentication process by receiving the call and confirming with the hash/pound (#) key on their phone that a successful hook-up has occurred.
The user is redirect to SharePoint whereupon (assuming permissions have been granted to the SharePoint site) they gain access.

We may employ authentication fall-back processes where the MFA provider supports it. Windows Azure Authentication Server, for example, offers the use of security questions as such a mechanism during logon.

This sort of flexibility should extend to other MFA providers via the adapter and bring their own capabilities to the fore.

Scenario 2 – Accessing the “Access Onion” Teamsite

This scenario is more complex as we have to take into consideration access requirements from multiple sources, in doing so hitting common challenges for Federated SSO concerning multiple organizations, realm discovery and authentication. Before we go into the obligatory diagram, we’ll recap on Home Realm Discovery (HRD), as it has a particular resonance in this scenario.

There’s no place like Home (Realm Discovery)

In AD FS 2.0, we are able to alter HRD behaviour either at the AD FS Proxy or AD FS Farm by changing the selector options visible to the user, for the claims providers concerned. This was possible by configuring the homerealmdiscovery.aspx.cs
code-behind page to suppress the providers that we didn’t want the user to see.

In AD FS R2, HRD customization options through PowerShell now allow us to determine how the UI is presented to the end-user during logon, based on:

target suffix resolution – providing suffix routing on a per claims provider basis
limiting the claims providers visible for the relying party concerned

With Option (a) we define the home claim provider of the target user, by binding the UPN domain/suffix of a particular set of users to a given claims provider. For example:

For users in the “Azure Sprout” organization with a @azuresprout.net
suffix, we send to the “Azure Sprout” claims provider.
For users in the “Access Onion” organization with a @accessonion.net
domain suffix, we send to the “Access Onion” claims provider.

With Option (b) we identify the claims providers we wish to use for that relying party, specifying which ones we wish to make them visible in the HRD list. This is governed on per relying party basis.

While having the flexibility of these options enhances functionality, they don’t eliminate HRD issues completely as we’ll see. Nonetheless, they can greatly simplify the user logon experience. You’ll ultimately need to find the right combination that works for you.

Back to the scenario. Users connecting externally in each organization should use multi-factor authentication (MFA). In addition, external users connecting through the “Access Onion” organization have an existing 3^rdparty MFA identity provider and their (external) users must use this provider.

Internal “Access Onion” Users

Represented by the orange numbered items in the diagram, internal user workflow should be as follows:

The User accesses the “Access Onion” Teamsite. The SharePoint Security Token Service (STS) has been configured to use the “Access Onion” AD FS as a trusted claims (identity) provider.
The user is redirected to the local “Access Onion” AD FS instance. Since the logon request is sourced from an internal user, the request is resolved via internal DNS, pointing to the “Access Onion” AD FS farm.
1. The Home Realm Discovery (HRD) process is invoked because there are three claims providers configured in the “Access Onion” organization:
  1. The local Active Directory claims provider
  2. The “Azure Sprout” claims provider
  3. A third-party claims provider (PointSharp STS) providing MFA.
Once HRD processing is complete, the logon process continues. Since the user is connected to the Access Onion LAN, the request is processed at the farm, whereby the user is silently logged on with their Windows credentials. A relying party rule is configured for the SharePoint Teamsite and claims rules (Send LDAP Attributes as Claims Rules) configured to pass the requisite attributes.
The user is redirect to the SharePoint “Access Onion” Teamsite whereupon, assuming permissions have been granted to the SharePoint site, they gain access.

For internal access, we don’t want “Access Onion” users to see the Home Realm Discovery (HRD) selection screens. The AD FS server, therefore, can be configured so that Intranet users can bypass HRD. This is accomplished by issuing the following command on the “Access Onion” AD FS instance.

Set-ADFSProperties –IntranetUseLocalClaimsProvider $True

External “Access Onion” Users

Let’s look at the logon workflow represented by the red numbered items in the diagram:

The User accesses the “Access Onion” Teamsite. Since the user is connecting externally, the URL of the SharePoint teamsite resolves to the IP address of the Web Application Proxy. On the proxy the request is intercepted and processed. A pre-authentication rule has been created for the SharePoint teamsite URL.
Before authentication can continue :
1. The Home Realm Discovery (HRD) is invoked because there are three claims providers configured in the “Access Onion” organization:
  1. The local Active Directory claims provider
  2. The “Azure Sprout” claims provider
  3. A third-party claims provider (PointSharp STS) providing MFA.
Once HRD processing is complete, the logon process continues and the user is routed to the 3^rd party claims provider. At the logon page, the user enters their credentials, using whatever authentication methods have been prescribed on the PointSharp Security Token Service (STS): Hard token, soft token, SMS etc. The STS is configured to pass back the appropriate attributes that will satisfy SharePoint Teamsite requirements via the AD FS RP-STS.
The user is then sent back to the “Access Onion” AD FS R2 instance, acting as an RP-STS. Here additional claims processing and authorization is for the SharePoint “Access Onion” Teamsite relying party.
The user is redirect to the SharePoint “Access Onion” Teamsite whereupon, assuming permissions have been granted to the SharePoint site, they gain access. The URL termination of this connection is at the Web Application Proxy and connections to SharePoint are reverse proxied through the WAP.

OK, let’s explore this a little further, particularly the realm discovery part. As mentioned in the previous section, the “Access Onion” AD FS R2 instance, beyond the default AD claims provider, has additional claims provider trusts with two claims providers: the “Azure Sprout” AD FS R2 Instance and the existing “Access Onion MFA” provider (PointSharp) running as a Security Token Service – PointSharp Identity Federation.

A user logging on externally to the “Access Onion” organization, by default, would be faced with the following sign-in options.

The blue icon represents the local “Access Onion” Active Directory claims provider.

With R2, we can reduce the number of visible CPs used via the two methods discussed in the HRD section, namely:

Use of suffix routing
Naming claims providers on the relying party concerned

For suffix routing, we can bind the suffixes used by each respective organization to target specific claims providers.

Set-AdfsClaimsProviderTrust –TargetName “Access Onion 3rd Party IdP” –OrganizationalAccountSuffix @(“accessonion.net”)

Set-AdfsClaimsProviderTrust –TargetName “Azure Sprout” –OrganizationalAccountSuffix @(“azuresprout.net”)

Users then see the following logon screen

The (PointSharp) 3^rd-party MFA provider is no longer visible, nor is the Azure Sprout organization. Clicking on the Other organization, we can then enter the appropriate suffix for the target claims provider.

The user is then routed to the “home” claims provider. Users with the @accessonion.net suffix, connect from externally, click on “Other Organization”, enter their credentials and are identified on the basis of the suffix entered, and routed to the in-house 3^rd party MFA claims provider; in this case a PointSharp Identity Federation Security Token Service (STS). Because AD FS R2 is acting as a Relying Party Security Token Service (RP-STS), it will route all users with this suffix to the PointSharp (claims provider) STS.

From here we continue the logon process, using whatever multi-factor authentication methods have been configured on the PointSharp provider.

A couple of comments at this point:

It would be nice to be able to customize the text for the “Other Organization” dialogue and screens. When I find out how this is possible or someone points me in the right direction, I’ll post an addendum to the article J
The base AD claims provider, “Access Onion”, is available in the HRD selection during external logon. While it was possible to suppress the base claims provider on the AD FS 2.0 Proxy, I’ve not worked out to do this under R2 for external clients. (Note: Disabling all the authentication types via the UI doesn’t suppress the AD provider). It’s a relatively minor point and one specific to this scenario, but the fact that it was possible under 2.0 grates a little. There could be a hidden parameter somewhere in the configuration that allows this…

Given the latter constraint, you’d be forgiven for trying Option (b) for HRD in this particular case. We can name preferred claims providers for our particular “Access Onion” Teamsite relying party by specifically limiting those we wish to see during logon for that RP. For example:

Set-AdfsRelyingPartyTrust -TargetName “SharePoint Access Onion Teamsite” -ClaimsProviderName @(“Access Onion MFA”, “Azure Sprout”)

This is a nice option for limiting web applications to given identity provider(s).

In this example, users are faced with the following logon screen when redirected to the “Access Onion” AD FS instance.

Great! No AD claims provider…..no really… I mean no AD claims provider J It prohibits the use of the AD provider in all login scenarios including internal ones, meaning that all users would now need to use MFA. While targeting identity providers is a useful feature, it’s not one applicable in this particular case.

Settings for the RP can be restored to normal by:

Set-AdfsRelyingPartyTrust -TargetName “SharePoint Access Onion Teamsite” -ClaimsProviderName @()

Based on the above behaviour, we’ll settle on using suffix routing for realm discovery scenarios.

Internal / External “Azure Sprout” Users

Let’s have at the logon workflow for “Azure Sprout” for users connecting from within their organization to the remote “Access Onion” SharePoint Teamsite. The logon flow, because MFA is a requirement, means that only the primary authentication mechanism changes, based on whether the user is connecting from inside the “Azure Sprout” organization (blue text) using IWA or outside (black text) using forms.

The User enters the “Access Onion” Teamsite URL. Since the user is connecting externally, the URL of the SharePoint teamsite resolves to the IP address of the Web Application Proxy. On the proxy the request is intercepted and processed. A pre-authentication rule is configured for the given URL.
Before authentication can continue :
1. The Home Realm Discovery (HRD) is invoked because there are three claims providers configured in the “Access Onion” organization:
  1. The local Active Directory claims provider
  2. The “Azure Sprout” claims provider
  3. A third-party claims provider (PointSharp STS) providing MFA.
Once HRD processing is complete, the logon process continues and the user is routed to the “Azure Sprout” claims provider. The primary (AD) authentication provider processes the logon request. When the user is connecting to the “Azure Sprout” local area network, the URL of the federation service resolves to the IP address of the internal AD FS farm. Internal users use their local Windows authentication in the primary slot, as can be seen by the Intranet configuration below.

External user logon, resolving to the external DNS of the Web Application Proxy, means that users employ forms-based authentication.
Having provided their AD credentials, the user must then satisfy additional authentication requirements and use their Windows Azure Authentication (MFA) credentials to continue further logon. This is enforced on the “Access Onion” Relying-Party STS as an MFA rule.
With logon complete the user is sent back to the “Access Onion” AD FS R2 RP-STS. Here additional claims processing, MFA checks and authorization for the SharePoint “Access Onion” Teamsite relying party take place.
The user is redirected to the SharePoint “Access Onion” Teamsite whereupon, assuming permissions have been granted to the SharePoint site, they gain access. The URL termination of this connection is at the Web Application Proxy and connections to SharePoint are reverse proxy through the WAP.

On the “Access Onion” SharePoint Teamsite relying party is a rule specifying all external users must use MFA.

This corresponds to the following additional authentication rule:

c:[Type == “http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork”, Value == “false”]=> issue(Type = “http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod”, Value = “http://schemas.microsoft.com/claims/multipleauthn”);

Similarly, in the “Azure Sprout” organization, the “Access Onion” AD FS instance is a relying party and this is where the MFA requirement is enforced. This corresponds to an additional authentication rule for the “Access Onion” AD FS Relying Party of:

“http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork”, Value == “false”] => issue(Type = “http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod”, Value = “http://schemas.microsoft.com/claims/multipleauthn”); c:[Type == “http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork”, Value == “true”] => issue(Type = “http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod”, Value = “http://schemas.microsoft.com/claims/multipleauthn”);

Earlier, on the “Access Onion” side, we hand-waved all logon requests to the “Azure Sprout” organization when setting up Home Realm Discovery (HRD) by using suffix routing.

Set-AdfsClaimsProviderTrust –TargetName “Azure Sprout” –OrganizationalAccountSuffix @ (“azuresprout.net”)

On the “Access Onion” AD FS side of things, we can validate whether MFA has been used during logon and the appropriate MFA claim value emitted by the “Azure Sprout” MFA Provider. On the “Access Onion” AD FS RP-STS, we create the following authorization rule for the “Azure Sprout” claims provider:

c:[Type == “http://schemas.microsoft.com/claims/authnmethodsreferences”, Value =~ “^(?i)http://schemas\.microsoft\.com/claims/multipleauthn$”]=> issue(Type = “http://schemas.microsoft.com/authorization/claims/permit”, Value = “PermitUsersWithClaim”);

On the “Azure Sprout” AD FS instance, we configure MFA as a requirement for the “Access Onion” relying party (RP-STS). All users in that organization then use MFA when accessing the “Access Onion” SharePoint Teamsite.

Logging on with our test user (training@azuresprout.net) using their UPN and password and we’re faced by the Windows Azure MFA Server required authentication.

As before, this second step involves the use of a call-back process and the test user I’m logging with receives a phone call, whereupon the hash/pound key has to be pressed to confirm I’m in possession of the device.

Logging on to a test WIF claims aware web application, we can see that a claim value is issued for use of the Azure MFA via phone confirmation. This illustrates that it is possible for MFA providers to provide custom claims in their (MFA) response to AD FS.

We can then access SharePoint, assuming the appropriate permissions are granted on the site concerned.

Let’s extend the scenario to see how MFA works with the a mobile device, such as an iPad.

MFA and Other Devices

I’ll use the same Workplace Join conventions I described in the first post, this time with MFA as an auxiliary logon mechanism. On the Device Registration Service (DRS) relying party itself, we’ll set a requirement for MFA to be used for unregistered devices.

From the iPad, we the Workplace Join process by entering the URL of the DRS endpoint in Safari. At this point we need to logon with our AD credentials.

Then we hit the MFA logon requirement.

Following a successful logon, we then start the enrolment process for Workplace Join on the iPad. The procedure at this point is the same as the one described in Part I. The user points their browser to an enrolment endpoint, e.g.

https://sts.azuresprout.net/Enrollment Server/otaprofile/

We install a profile.

Once completed and there is a successful join to the workplace, the device is registered within AD and a certificate installed in iOS. Device authentication then becomes available as a qualifier when setting conditional access policies to permit access to the enterprise network.

Let’s look at an example using the “Azure Sprout” AD FS configuration accessing the “Access Onion” SharePoint Teamsites. Redirected to AD FS R2 instance during logon, the certificate is used to assert the identity of the user on this device.

The HRD screens sign-in screens are similar to those we saw earlier on a Windows PC using Internet Explorer.

Click on the Other Organization link and enter training@azuresprout.net
our as user for logon. The use of @azuresprout.net ensures that the user is routed to the “Azure Sprout” organization.

At the “Azure Sprout” AD FS the user must logon with their AD primary authentication credentials.

With MFA enabled on the AD RP-STS rule for the “Access Onion”, the connecting user must satisfy the MFA logon requirement with Azure MFA phone authentication:

A call is made to the user phone to confirm authentication. Logon can continue.

Claims are processed on the claims provider pipeline and then on the SharePoint relying party, and we’re into the SharePoint Teamsite. Having logged on with our user/device pairing, the SSO features of Workplace Join now come into play. The user registered to the device is now issued with an SSO token that is persisted for 7 days (default setting). Subsequent logons by that user will only require validation of the SSL device certificate when accessing AD FS until the token expires.

This persistence behaviour can be adjusted via the Set-ADFSProperties –PersistentSSOLifetime setting (minutes). To disable this, we can use the following command:

Set-AdfsProperties -EnablePersistentSso $False

Don’t forget when testing that the SSO experience is bound to the user and device pairing. Logging on with another user will not exhibit the same behaviour.

MFA with Non-claims Aware Web Applications

All the examples to date have been with claims-aware web applications. R2 also provides support for relying parties that are non-claims aware using the kerberos protocol. This is a great feature and the combination is made possible by creating a non-claims aware RP within AD FS and then making the application available through publishing it via the Web Application Proxy (WAP) using Kerberos Constrained Delegation between the front-end WAP and the back-end web application. This, of course, means that the Web application Proxy must be domain-joined.

In the test below four servers have been used, with all servers member of an Active Directory (a-onion.local):

Role	Server Name (FQDN)	Web application FQDN (web.accessonion.net)
		Internal (Kerberos)	External (MFA)
R2 Domain Controller	server111.a-onion.local
R2 AD FS Server	server222.a-onion.local
R2 Web Application Proxy	server555.a-onion.local		X
R2 Application Server (IIS)	server333.a-onion.local	X

Access to the IIS application is through a qualified name of web.accessonion.net rather than the actual name of the server. The kerberos web application is reachable internally via DNS using the URL of https://webaccessonion.net. The app itself is a vanilla IIS web page protected using Integrated Windows Auhtentication (IWA).

Here’s an overview:

This was tested using the “Azure Sprout” organization only. There’s no RP-STS, other AD’s etc. to speak of in this configuration

Let’s quickly go throw the configuration steps.

On the IIS server enable Integrated Windows Authentication (IWA) on the IIS website. In real life, this is more likely to be a given path rather than the website itself.
Test access internally by adding the FQDN of the website URL into the Local Intranet Zone of the browser (Internet Explorer). Here we’ve add the https://web.accessonion.net
URL to that zone security list.

If you continue to be prompted with NTLM Challenge/Response, check that the SPN for the URL of the web application has been registered under the computer account (in a web farm scenario this would be an application pool). For example:

SETSPN –S http/web.accessonion.net a-onion\server333
On the domain controller or a client with remote administration tooling installed, run the ADSI Edit snap-in, drill down to the Web Application Proxy computer object, right-click, select properties. Add a Service Principal Name (SPN) for the computername of the Web Application Proxy, together with the fully qualified name.

Using the examples from the diagram, this would translate to:

http/server555.a-onion.local

http/server555

In AD Users and Computers (ADUC), on the delegation tab of the WAP computer account (server555.a-onion.local), add the computer account for IIS (server333.a-onion.local) as being trusted for delegation for HTTP (ms-DS-AllowedToDelegateTo)
Create the non-claims aware relying party within the AD FS UI using the URL and path of the web application as the RP identifier (don’t forget the trailing slash)
Specify that an MFA rule will apply to this relying party
External Users are required to use MFA
We’ll use the default authorization rule of Permit All.
On the Web Application Proxy, create a publishing rule for the non-claims aware relying party.
On the Web Application Proxy, we configure the rule for https://web.accessonion.net/ together with the SPN of the back-end web server (http/server333.a-onion.local).

External clients should now be challenged for MFA when accessing the IIS Web Application. I’ve used a workplace joined Windows 8.1 device using Chrome to highlight this (NB: IE11 doesn’t challenge for the device certificate).

Logging in with forms-based logon (primary authentication)

The additional authentication rule executes for the MFA provider for logon:

The user gets called back, as per the previously described method. Once they’ve responded, redirection to the non-claims aware IIS web application, our vanilla IIS splash-screen.

So that’s it for now. I’ve glossed over some of the finer details in this post and apologies for any brevity. If you do require more information, please post in comments and I’ll try and answer quickly. Meanwhile, we’ll cover more fine-grained access control decisions in Part III, as well as Work Folders, Server Core installation and (time-permitting) some OAUTH access scenarios.

Until then ….Happy New Year!

First Impressions – AD FS and Windows Server 2012 R2 – Part I

September 13, 20132FA, AD FS 2.0, AD FS 2.1, AD FS 2.2, Claims-based Authentication, MFA, Multi-Factor Authentication, Windows Server 2012 R2AD FS, AD FS 2.0, AD FS 2.1, AD FS 2.2, AD FS R2, Claims-based Authentication, MFA, Multi-Factor Authentication, Windows Server 2012 R2, Workplace Joinmylo

In the next few posts, I wanted to take a look at the changes to be found in Windows Server 2012 R2 with respect to Active Directory Federation Services (AD FS). At TechEd Europe, I was fortunate enough to chat with some of the folks from the Active Directory team about the new enhancements and to cover them here in a little more detail. As you may have read, there are a significant number of changes in the R2 version and I’ll spread coverage of this over a number of posts.

Part 1

– Architecture Changes

– Workplace Join / Bring Your Own Device (BYOD)

o Windows 8.1

o iOS Devices

– Web Application Proxy

– Extranet soft account lockout policies

– Lost Device Protection

Part 2

– UI Changes

– Access Scenarios

– Authentication changes

o Multi-Factor Authentication

o Context-based Authentication

o Claims/Non-claims aware applications

o Policy-based Evaluation

Part 3

– OATH2 support

– Work Folders

– Better event handling / reporting

– Server Core

– Other stuff undiscovered J

Architecture Changes

The use of IIS with AD FS in Windows Server 2012 R2 has been eschewed in favour of a move to kernel-mode (HTTP.SYS). The motive, highlighted in discussions at TechEd, is to improve performance, provide greater sign-in customization options and to assuage concerns for co-locating AD FS and AD DS on the same server (IIS on domain controllers has been a long-standing security no-no). As the use of federation services goes more mainstream in everyday use with Windows 8.1, this shift is understandable and an important design consideration. With the new kernel-mode approach, support for running under server core also appears as an option in the new release.

From a basic architecture standpoint and overview, the AD FS proxy has been supplanted by a role known as the Web Application Proxy, servicing connections for external clients. The user interface (UI) through the migration to kernel mode is also significantly changed. Authentication undergoes a radical overhaul with a Multi-Factor Authentication (MFA) Adapter available for plugging into Windows Azure Active Authentication and third-party MFA providers. This is also seen in more nuanced behaviour with respect to authentication within the product, reflected in greater flexibility in access control decisions.

With AD FS now built directly built on top of HTTP.SYS, a lot of changes are abstracted from the user through the new MMC UI and also PowerShell. Nonetheless, it’s worthwhile familiarizing ourselves with kernel mode elements, as they serve a useful role in basic service troubleshooting/configuration . The NETSH HTTP command can be used to query and configure http.sys.

The netsh http show urlacl command can be used to list URL reservations that AD FS makes within http.sys. Here we can see the /adfs/ path reserved for use.

Reserved URL : https://+:443/adfs/

User: NT SERVICEadfssrv

Listen: Yes

Delegate: Yes

SDDL: D:(A;;GA;;;S-1-5-80-2965554544299-213434830-363436364-117610243-975697593)

And there’s this new guy, the Device Enrolment server, whose role becomes more apparent should we wish to make use of new Windows 8.1/iOS client (mobile) integration features.

Reserved URL : https://+:443/EnrollmentServer/

User: NT SERVICEdrs

Listen: Yes

Delegate: Yes

SDDL: D:(A;;GA;;;S-1-5-80-1321940109-3370001082-3650459431-215109509-2472514016)

SSL bindings can be reviewed using the netsh http show sslcert command. The AD FS server in this demo setup I’ve created is sts.adfs2.net.

PS C:Windowssystem32> netsh http show sslcert

SSL Certificate bindings:

————————-

Hostname:port : sts.adfs2.net:443

Certificate Hash : 1f54c1c62b057dscffgb1aec2b2cbd0876e5c559

Application ID : {5d89a20c-beab-4389-9447-324788eb944a}

Certificate Store Name : MY

Verify Client Certificate Revocation : Enabled

Verify Revocation Using Cached Client Certificate Only : Disabled

Usage Check : Enabled

Revocation Freshness Time : 0

URL Retrieval Timeout : 0

Ctl Identifier : (null)

Ctl Store Name : AdfsTrustedDevices

DS Mapper Usage : Disabled

Negotiate Client Certificate : Disabled

Hostname:port : localhost:443

Certificate Hash : 1f52c0d62b0570c6a26c7fec2b2cbd0876e5bc59

Application ID : {5d89a20c-beab-4389-9447-324788eb944a}

Certificate Store Name : MY

Verify Client Certificate Revocation : Enabled

Verify Revocation Using Cached Client Certificate Only : Disabled

Usage Check : Enabled

Revocation Freshness Time : 0

URL Retrieval Timeout : 0

Ctl Identifier : (null)

Ctl Store Name : AdfsTrustedDevices

DS Mapper Usage : Disabled

Negotiate Client Certificate : Disabled

Hostname:port : sts.adfs2.net:49443

Certificate Hash : 2f5c41c62b0570c6a26c7fec21d2d0876e5c559

Application ID : {5d89a20c-beab-4389-9447-324788eb944a}

Certificate Store Name : MY

Verify Client Certificate Revocation : Enabled

Verify Revocation Using Cached Client Certificate Only : Disabled

Usage Check : Enabled

Revocation Freshness Time : 0

URL Retrieval Timeout : 0

Ctl Identifier : (null)

Ctl Store Name : (null)

DS Mapper Usage : Disabled

Negotiate Client Certificate : Enabled

Location-wise, the AD FS application files themselves are no longer held under C:Program FilesActive Directory or C:Program Files (x86). Instead, they’ve moved to C:WindowsADFS. For clarity, this was actually a change instigated first in Windows Server 2012 with the Active Directory Federation Services (AD FS) 2.1 role. In this folder is the Microsoft.IdentityServer.Servicehost.exe.config file, where, as admins, we’ll be spending more time in the future in order to activate debug functions. From this file all trace options for various services and endpoints can be enabled. In the same folder is a configuration file for the new Device Registration service (DRS), responsible for activation and enrolment of controlled devices and represented by a new (Win8/IOS *) schema class in Active Directory Domain Services (AD DS). The file in question is called Microsoft.DeviceRegistration.ServiceHost.exe.config.

Support for the new Device class requires a schema change to Active Directory. For those upgrading an existing Windows setup, the appropriate files can be found on the R2 installation CD under D:SupportADPrep. From what I’ve seen/tested thus far, to support the new release, you’ll need at least one Windows Server 2012 domain controller, preferably two in any serious deployment scenario. This requirement stems from the use of Group Managed Service Accounts (GMSA) that are generated and maintained by the Key Distribution Service (KDS) on 2012 domain controllers. The new version of AD FS makes use of these GMSA accounts, defined during AD FS installation, that are then shared amongst connecting AD FS hosts. I suggest reading the following backgrounder and bear in mind that the AD FS Windows Server 2012 preview labs incorporate a workaround for testing purposes, in activating the root key, that is not recommended for production environments.

Update 29/10 – SamD from the AD product team added that “gMSA is not required to be the service account that ADFS runs on. It is an additional optimization that is available to customers if they have Win2012 domain controllers available.” The traditional service account option is available during installation.

Moving on, let’s take a look at the “broader” access audience that the new version emphasises. This can be immediately seen by viewing the claims descriptions list surfaced on a new AD FS installation.

There are around 40 new claims descriptions available in the AD FS Windows Server 2012 R2 release. As we’ll see, use of these new claims types allow us to make more refined assessments concerning access to web applications and resources.

Workplace Join / Bring Your Own Device (BYOD)

Through the new Workplace Join feature within R2, AD FS becomes a focal point for mobile access in the enterprise and an integral component in the Microsoft Bring Your Own Device (BYOD) vision. Workplace Join allows hitherto unmanaged/untrusted operating systems such as Windows RT/Windows 8 and IOS to be moved into a more controlled access context, by allowing their registration and affiliation with Active Directory. Devices will register with Active Directory through a Device Registration Service (DRS) and subsequently use an X509 certificate bound to the user context(s) on that machine for device authentication. In a default configuration, users will login via AD FS to initiate the join process using their AD credentials. To further secure this process, additional factors can be also used with Windows Azure Active Authentication (PhoneFactor) or a third-party authentication provider exposed through the new AD FS MFA SDK.

Devices that are workplace-joined emit additional claims during the logon process. These include:

Certificate support in claims handling has also been enhanced.

Windows 8.1

In order to provide a comparison between old and new with Workplace Join, I began by looking at what claims (and any new ones) are processed from a vanilla Windows 8.1 Pro domain-joined machine, using a simple WS-Federation relying party to validate claims emitted the client and AD FS components.

Firstly via the internal network and the AD FS farm using Internet Explorer. Here the browser uses Integration Windows Authentication/Negotiate and the user silently accesses to the WIF relying party via Kerberos. The usual configuration caveats apply here: the URL of the AD FS and RP instance are in the Local Intranet Zone of IE.

To demonstrate a new change, I installed Mozilla Firefox and repeated the logon process. Instead of the Integrated Windows Authentication (IWA)/Negotiate process, the user is presented with a forms sign-in page. This represents a departure from the user experience and behaviour in AD FS 2.0. With the latter, authentication would be downgraded to NTLM, because IWA was assumed in the farm configuration and the browser needed to be configured to explicitly support Kerberos for seamless login. Where the latter action was not performed, the user would receive an NTLM challenge/response prompt, often causing confusion. With the new release, support for IWA is now governed through setting registering User Agent types within AD FS that are capable of supporting Negotiate. Out of the box, this is constrained to IE, meaning any other browser will revert to using forms logon when accessing resources from an internally connected client . Here we see the claims output from a Firefox login:

In internal login scenarios (IE/Firefox), we see new claims types emitted concerning location (whether the login request is sourced within the Corporate Network), an Application Identifier (corresponding to the Relying Party Identifier), the Client source IP (or translated) address, an Authentication Method Reference and a Client Request ID.

Then, via an external network through the new Web Application Proxy:

In addition to those claims types mentioned earlier is a new claims type for the client forwarded IP (x-ms-forwarded-client-ip) processed at the Web Application Proxy. The insidecorporatenetwork value is now set to false, as we’re on an outside network.

You may have observed at this point that there are no Device claims. This makes sense if we consider that their use is limited to client types that declare them, i.e. only workplace-joined clients currently make use of the Device class.

Onto the workplace join process itself. To get your test lab up and running, I recommend reading this TechNet article.

If you follow the lab guide carefully, and, in particular, with emphasis on getting the dependent infrastructure working correctly, then with a little patience and time, you’ll be up and running. I tried this with the basic contoso.com lab setup (a good starting point) and then expanded this in new setup using my own test domain. There are a few gotchas worth pointing out, hoping that you’ll avoid my growing pains …

1. Don’t use Cryptography Next Generation (CNG) algorithms when configuring your AD Certificate Services. They won’t work.

2. For simplicity in your CA configuration, I’d opt for use of HTTP Distribution endpoints, particularly if you intend to test “outside” configurations using the Web Application Proxy. Ensure the Certificate Revocation List (CRL) on the Certificate Distribution Point (CDP) and your Authority Information Awareness (AIA) URLs are setup correctly and reachable from the Win 8.1 client. If you’re using Delta CRLs and IIS as the web server for your CDP, don’t forget to allow Double Escaping on IIS in the Request Filtering section.

3. Ensure the Enterprise CA is trusted by the client and the certificate is installed in the Trusted Root Authorities section of the client. Importing the cert via the AIA endpoint is a good way of testing its availability and installing the certificate. Again, the certificate distribution point (CDP) URLs should be visible to the client.

4. Issue the AD FS certificate, complete with SAN for the Device Registration Service (DRS), before you begin your AD FS setup. The common name (CN) on the certificate should be the AD FS URL and two Subject Alternate Names (SAN) entries should contain the AD FS URL and one for the Device Registration Service (DRS) provided. For example, I’ve used an example using the MMC snap-in Certificate Request wizard, based on a copy of the default Web Server template for a common name of sts.mydomain.com for the FQDN URL of the AD FS service and also as the first Subject Alternate Name (SAN) entry. A second SAN entry is used for the DRS endpoint, enterpriseregistration.mydomain.com.

5. As posted on the Technet forums (in the current R2 preview), both the AD FS server and the Windows 8.1 client need to be configured with time-zone of UTC 0:00 or less. My setup is using Pacific Time (UTC -8:00). Don’t ask me, I just blog here J

6. Don’t forget to enable Device Authentication in Global Primary Authentication settings within the UI or via PowerShell.

7. Use the Event Log Microsoft|Workplace Join to troubleshoot!! Here’s a collage of first-hand events to illustrate it’s effectiveness in troubleshooting:

URL (enterpriseregistration.xxxx.yyyy) cannot be resolved or reached.

Can’t reach the CRL CDP of the AD CS endpoint.

Root Authority is not trusted by the client.

This message is stating a number of possible issues (generally bad):

o DRS Configuration and Activation was not completed successfully

o Issues with the SAN on the SSL certificate

o AD FS Device Authentication has not been enabled

Once you start seeing messages like the following, you’re almost there.

Nice.

8. Take particular note of any errors reported when trying to activate Device Registration Service; namely anything along the lines of:

WARNING: UPN values that are not included in the SSL certificate have been found in the enterprise. Users with these UPN suffix values will not be able to register their devices. To enable users with the corresponding UPN suffix to register their devices, provide a new SSL certificate containing the values listed below in the subject or subject alternative name.

enterpriseregistration.upn1.contoso.com
enterpriseregistration.upn2.contoso.com

In the case of (8), I’d made the mistake of not registering the appropriate certificates with Subject Alternate Names (SAN) that included the DeviceRegistration CNAME record. Simply re-issuing the AD FS service certificate afterward, setting Manage Private Keys etc. and re-activating DRS in PowerShell was not sufficient to get the configuration working.

The Workplace Join function can be accessed by first accessing the Change PC Settings option on the Windows 8 UI

In PC Settings, choose the Network option

Then select Network followed by the Workplace option:

If your configuration is working, certificates are trusted, appropriate AD FS and PKI endpoints are reachable, stars are in alignment (just joking), then clicking on the Join button leads to AD FS responding with a challenge:

Enter the Active Directory credentials for the user. In this example I’m using, the device is joining a test domain called adfs2.net. Note the AD FS URL (connecting to my R2 instance sts.adfs2.net) at the top of the page. For the auto-discovery of the AD FS Device Registration Endpoints (DRS) a CNAME (Alias) record in DNS needed to be created for the service called enterpriseregistration.adfs2.net. This record points to the host (A) record of the AD FS federation service internally. This allows the discovery process to find the DRS endpoint and in an external setting this would point to the Web Application Proxy, your own Reverse Proxy or other suitable edge device.

The relying party (RP) for the Device Registration Service is created during the DRS activation process, so there’s nothing additional required on this side.

Connecting Windows 8.1 clients will use the auto-discover function by matching the domain suffix of the user account provided during the join process against the enterprise registration CNAME record for that domain. The join process then attempts a call to the enrollment server web service. Using the adfs2.net domain as an example, the following endpoint is queried:

https://enterpriseregistration.adfs2.net/EnrollmentServer/contract?api-version=1.0

If the service can be reached successfully, the join process is initiated.

The process is now completed and the “join” associated with the Windows 8.1 user profile. I used a Microsoft Live ID account and as can be be seen from the above screenshot, a subsequent AD user called demo with a UPN of demo@adfs2.net,in doing so providing my AD credentials during the Join. Please note that the Active Directory domain I’m using is also called adfs2.net (dc=adfs2,dc=net) for convenience. In a real-world/production scenario, the DNS domain names used for Active Directory and that of the federation service itself may be different.

The user account is then issued with a self-signed X509 certificate with an Extended Key Usage (EKU) of Client Authentication. Jumping into the Certificates|User snap-in we see a certificate issued under the user context.

Back to the WIF 3.5 relying party (RP), logging on to the RP from the outside we get redirected to AD FS for logon. Upon successful logon, the following claims are shown.

With the Win 8.1 device now connected to the AD domain via a Workplace Join, we see additional claims consummated.

· IsRegisteredUser

· OS Version

· OS Type

· Identifier (Subject name of the cert)

· Display Name (corresponding to the Device Name)

· Registration ID (corresponding to an OU served up in the certificate)

The device itself is registered within Active Directory at the following location: CN=<Device ID>,CN=RegisteredDevices,DC=mydomain,DC=com.

Here’s an example with a SAML 2.0 Service Provider (SimpleSAMLphp), with a Workplace Joined Windows 8.1 client connecting to it.

Inside the corporate network, we see the following:

As tempting it is to delve further into authentication, I’ll refrain from doing so and leave this to a follow-up post. My apologies, otherwise this post will reach biblical proportions in length and we’ll be shaking hands with Santa Claus before we know it.

iOS devices

From testing, the auto-discover function using the enterpriseregistration CNAME record in DNS, described in the previous section, is limited to the workplace join process for Windows 8.1. iOS clients must directly connect to AD FS to initiate the join process. The endpoint settings on the DRS Relying Party refer to a URL of:

https://sts.adfs2.net/Enrollment Server/otaprofile/

This is the DRS Over-the-Air endpoint for non-Windows devices (currently iOS only).

I used an iPad 3 running iOS 6.1.3 for this exercise. If you plan on using self-signed certificates for this type of testing, you’ll need to use the iPhone Configuration Utility to create a profile which can be then used to install the root certificate from your Certificate Services Issuing CA (and any optional chain).

If you’re testing iOS or Windows 8.1 devices in an external setting, it’s worth mentioning that the Web Application Proxy (WAP), which I’ll cover in a moment, doesn’t provide an HTTP Reverse Proxy function. To ensure that any CRL/AIA distribution points are visible in an “outside” testing context, I elected to install IIS on the WAP, publish the CRL/AIA Certificate Distribution Points (CDP) via a UNC from the CA itself to be made available as an HTTP URL on the Web Application Proxy via IIS, making the distribution points reachable from an external perspective. Clearly, this is not something one would do automatically in a production environment, without a bit of forethought, but it works well in a demo environment. You can probably also do this with a kernel mode only approach, but I didn’t have time to test this (yet).

Once the Apple configuration file (.mobileconfig) file had been deployed onto my iPad (via e-mail), a Profile containing the Root certificate was generated and the certificate installed.

With the root certificate or chain correctly installed, going to the AD FS server URL, we should not receive any SSL errors or warnings in the browser, indicating that the chain and CRL/AIA distribution points are reachable. To test this, you can use the IdP initiated sign-on page in the default setup, e.g. https://YOURFQDN/adfs/ls/idpinitiatedsignon.aspx. From the iPad, here’s the portrait view of the page.

Playing around, I turned the iPad on its side and we get an automatically resized window. This is a nice feature in the new UI in AD FS 2012 R2 that supports dynamic adjustment and positioning of elements through CSS, resizing pages accordingly across various devices and user agents (think mobile client).

In order to kick off the Workplace Join, we point Safari to the endpoint DRS mentioned earlier:

https://sts.adfs2.net/Enrollment Server/otaprofile/

This redirects the browser to a sign-in page where we need to logon with the AD account that will be bound to the iOS device for the workplace join.

Logging on with the demo@adfs2.net account I used in the Windows 8.1 example, the Safari page remains open in the background and the foreground switches to the install profile option on the mobile device.

The install profile option and Workplace Join install option appears:

Clicking on the More Details option, we can see that the AD FS Token Signing Certificate (public key) and the Device Enrollment Encrypted Profile Service are referenced during the profile installation.

Clicking on Install Profile

Once the profile is installed we see a Certificate issued to the device, issued with a common name of MS-Organization-Access, as per the Windows 8.1 join process.

Returning to the profile screen we see the completed Workplace Join profile

NB: The Demo Auth360 profile is the imported .mobileconfig containing the root certificate from earlier.

Web Application Proxy

Sitting in front of the AD FS farm is a new optional role, similar to the AD FS Proxy in AD FS 2.0, called the Web Application Proxy. This is a completely redesigned component, built to cater for federation services scenarios as well additional access scenarios beyond those seen in AD FS 2.0.

As with DirectAccess in Windows Server 2012, more roles are being moving into the mainstream product and the Web Application Proxy is a module in the Remote Access role within Windows Server 2012 R2.

Configuration of the proxy itself also moves to the Remote Access Management snap-in.

A configuration wizard is provided to connect the proxy to the back-end AD FS farm and a service account is required to register with the AD FS server(s) during installation. This service needs to be a member of the local administrators group on the AD FS farm.

Once connected to AD FS, a number of simple options are available for configuration.

The UI is at this stage is admittedly basic, but as with DirectAccess in 2012, there’s a greater emphasis on using wizards to get the job done and whatever can be done in the UI can be done (and more) via PowerShell; a PS configuration script is provided as a summary at the end of each publishing wizard rule to demonstrate this point.

As with TMG/UG we can publish/proxy a particular URL or URIs/paths of that URL expressed as separate publishing rules on the proxy , e.g.

www.mydomain.com/ (as one allow all rule) versus

www.mydomain.com/app1/ as Rule#1

www.mydomain.com/app2/ as Rule#2

www.mydomain.com/app3/ as Rule#3

An interesting under-the-covers capability is support for Server Name Indication (SNI). SNI, initially provided in Windows Server 2012, allows for multiple certificates to be bound to a single IP listener. Prior to IIS 8.0/SNI, sharing IP addresses amongst multiple websites was limited to the network endpoint and their IP:Port binding. SNI is a TLS extension that provides the hostname of the server the client is connecting to during handshaking. This allows much greater flexibility when configuring the proxy. With the move to kernel-mode, all the hard lifting is done through the UI or via PowerShell. familiarity with NETSH HTTP will also assist in any troubleshooting or ad-hoc configuration. The majority of browsers support SNI, although Windows XP in any configuration using Internet Explorer does not.

The current preview of the proxy in the R2 release provides for connections as:

1. A reverse web proxy, connecting to back-end servers via HTTPS;

2. A pre-authentication web proxy, connecting to AD FS via HTTPS to validate credentials

a. For claims aware web applications

b. For non-claims aware web applications using Kerberos

When we publish a new AD FS compatible application (pre-authentication), the proxy pulls the RP list/ configuration from the AD FS farm. Polling is done (looking at the event logs) every minute.

Using a Windows Identity Foundation (WIF) test relying party application from another test domain (psid.local), here’s an example of a publishing rule:

Add-WebApplicationProxyApplication -BackendServerUrl ‘https://rp.psid.local/app9/’ -ExternalCertificateThumbprint ’91D8014979B9CDEF9C907171F7CE9AF398E66DC6′ -ExternalUrl ‘https://rp.psid.local/app9/’ -Name ‘WIF Test Application’ -ExternalPreAuthentication ADFS -ADFSRelyingPartyName ‘WIF 3.5 Application’

This is a pre-authentication rule, meaning that AD FS process the login request, UI surfaced and validates access and authentication credentials through the proxy via a back-channel connection before access to the relying party is processed.

To complete this round of testing, I wanted to validate Workplace Join from an “outside” network via the proxy. DRS endpoints are automatically published, meaning no specific additional publishing rules needed to be created.

On the Windows 8.1 client, I removed the client from the Join agreement created earlier in order to re-attempt the join via the proxy from the external network. When we attempt a join again from the “outside” via the Web Application Proxy, clicking on Join generates the following page.

The user ID is automatically populated in the form, carried over from the Join request.

Testing from the “outside” now, when we access our WIF application RP from our Workplace Joined client (via the Web Application Proxy), we’re served up with a sign-in form.

That’s expected as we’re now an Extranet client (using MS terminology). This is confirmed by looking at the base AD FS configuration and the primary authentication provider serving up forms login for external clients.

“Extranet” users are automatically assigned to the forms authentication sign-in process, whereas Intranet users are assigned Windows Authentication, browser considerations notwithstanding. For those familiar with fiddling with Local Authentication Types in web.config on the AD FS proxy/farm in AD FS 2.0, making this available through the UI and Powershell is a boon J

Going back to our relying party application, we can see in the produced claims that the client connection is not through the corporate network and is via Web Application Proxy using the following claims:

http://schemas.microsoft.com/ws/2012/01/insidecorporatenetwork

http://schemas.microsoft.com/2012/01/devicecontext/claims/isregistereduser

The client is outside the corporate network and the user is now registered. As a simple test, if we only want to allow Registered Users access to our RP claims web application, we could do this through an Authorization Rule that states that only Registered Users are permitted access:

c:[Type == “http://schemas.microsoft.com/2012/01/devicecontext/claims/isregistereduser”, Value =~ “^(?i)true$”] => issue(Type = “http://schemas.microsoft.com/authorization/claims/permit”, Value = “PermitUsersWithClaim”);

Logging on with a non-workplace joined client from outside the corporate network, we are denied access.

Error pages are customizable and that’s something we’ll cover in Part 3.

As I touched on earlier, we can use SSL bridging scenarios incorporating wildcard certificates on the front-end (proxy) and named certificates (on the back-end) in publishing scenarios. The pre-authentication parts allows integration with claims and non-claims aware (Kerberos) applications. Applications such as Exchange, which are not claims-aware or non-SAML kerberos claims SharePoint web applications can be configured via the Web Application Proxy. From testing rich client applications such as ActiveSync and Outlook, which use Basic/NTLM application, these are not currently supported on the Web Application Proxy either in a pre-authentication or pass-through capacity. The proxy defaults to SNI and this is not supported by some mail clients. We’ll cover this and other authentication scenarios in Part 2.

Just to wrap up, here are some observations from testing:

– The proxy can translate host names in URLs but not path names. Make sure that the published path matches that of the application;

– There’s no Edit function in the UI once you’ve created a publishing rule;

– The Web Application Proxy is currently HTTPS only, so no HTTP publishing. Hopefully this will be corrected in the near future as scenarios such as CRL/CDP publishing, which use HTTP are not supported in Reverse Proxy scenarios today. Meanwhile, HTTPS-HTTP bridging, sometimes used in Kerberos Constrained Delegation (KCD) scenarios with TMG/UAG are also not possible as AD FS is HTTPS only.

Extranet Soft Account Lockout

Extranet soft account lockout imposes an option to temporarily lockout “extranet-connected” accounts, via the Web Application Proxy, by not incrementing the AD BadPassword count on the PDC Emulator in AD once the soft lockout threshold is set in AD FS. If the latter is reached, further logon requests are not passed to AD so that AD Password Policy “hard” lockout measures are not immediately triggered. As the name suggests, this is a soft lockout option that is governed by use of an observation/sliding window that determines how often in a given period a user may attempt to logon via the proxy before the soft count is reached. The goal here is to frustrate password guessing attempts via brute force/DoS from the outside by nefarious users.

Update 29/10 – SamD from the AD product team mentioned that the extranet lockout feature was also done with the view that customers with ADDS account lockout policies can prevent DOS attacks on specific user accounts by setting a threshold lower for the ADFS extranet lockout policy. This way the user still has internal access because ADDS has not locked out the user.

Soft Account Lockout can be invoked through the use of PowerShell.

$observationwindow = New-Timespan -Minutes 1

Set-ADFSProperties –ExtranetLockoutThreshold 3 -EnableExtranetLockout $true -ExtranetObservationWindow $observationwindow

Once set, we can see via Get-ADFSProperties, the changes applied:

ExtranetLockoutThreshold : 3

ExtranetLockoutEnabled : True

ExtranetObservationWindow : 00:02:00

Here we’ve set the lockout threshold to three attempts with an observation window of two minutes.

From a testing standpoint, In the demo AD Domain setup, “hard” account lockout is not set via GPO.

Attempting to login at the RP WIF test application, we’re redirected to AD FS for logon. I enter an incorrect password.

The PDC Emulator FSMO role in AD, which monitors the bad password count (badPwdCount) increments by 1, likewise on the second and third bad password attempts.

I entered a bad password five times in successive attempts. Continued attempts to logon with a bad password, once the observation window kicks in fails to increment the count beyond three for the windowed period of two minutes. Once the window has elapsed, the bad password account is again incremented.

One of the nicer aspects of this setting is that it applies to all endpoints, be they passive or active in nature. This is particularly relevant as it also applies to web services (WS-Trust) endpoints for rich clients, e.g. Office 365.

Lost Device Protection

As covered earlier, devices registered via Workplace Join are registered within Active Directory in the container CN=<Device ID>,CN=RegisteredDevices,DC=mydomain,DC=com. Lost devices can be denied access by disabling or deleting the appropriate object within AD (I moved the device objects to another OU to test this). Access through AD FS is immediately revoked for the workplace joined client.

From testing thus far, devices joined, left and re-registered via Workplace Join are not currently cleaned up within the RegisteredDevices container. Some PowerShell scripting is currently required to enforce this and I would imagine some changes by GA or some scripts made available to manage this process.

Summary

A very long post comes to an end. Next up, we’ll look at UI changes and authentication/access in greater detail and there’s LOTS to cover. As ever, please feel free to comment, contribute, correct and I’ll get back to you!

Step-up Authentication Scenarios with AD FS 2.0 Part II

July 30, 20132FA, AD FS 2.0, Certificates, Claims-based Authentication, MFA, SAML 2.0, Windows Server 2012 R2, WS-FederationAD FS 2.0, Claims-based Authentication, MFA, Multi-Factor Authentication, SAML 2.0, Windows Server 2012 R2, WS-Federationmylo

With the R2 preview of AD FS in Windows Server 2012 out and the large number of changes that are taking place in the new release, I’m going to be bring this post to a quick end; more an abridged version than was originally intended.

In Part I we looked at weaker authentication schemes for step-up scenarios. In Part II, we move onto two-factor/multi-factor authentication (2FA/MFA) use cases.

There’s no real guided approach for doing this in AD FS 2.0, with solutions invariably becoming customized ones, according to the desired use case. Whether AD FS is the authentication provider or occupying a hybrid/broker role, the use of authentication contexts, types and URIs provided by the supported SAML and WS-Federation protocols, become triggers for step-up. Where a context is stipulated, in protocol terms, each is interpreted differently.

SAML supported authentication methods

Authentication Method	Authentication Context Class URI
Username/Password	urn:oasis:names:tc:SAML:2.0:ac:classes:Password
Password Protected Transport	urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport
Transport Layer Security (TLS) Client	urn:oasis:names:tc:SAML:2.0:ac:classes:TLSClient
X.509 Certificate	urn:oasis:names:tc:SAML:2.0:ac:classes:X509
Integrated Windows Authentication	urn:federation:authentication:windows
Kerberos	urn:oasis:names:tc:SAML:2.0:classes:Kerberos

As we saw in the previous post, forcing authentication in SAML logon scenarios provides support for step-up, but at the expense of single sign-on. In passive federation scenarios, if we don’t specify an authentication method in the request, AD FS will apply authentication according to its own supported methods, attempting to match those against the local authentication types section of the web.config on the AD FS node.

AD FS handles the SAML authentication in order of strength, lowest to highest, from top to bottom as seen in the table: in the default configuration Kerberos is seen as the strongest method. The precedence of the authentication method can be adjusted using the Set-ADFSProperties –AuthenticationContextOrder command to ensure the order meets the requirement we need. The SAML comparison attribute can be used to also influence the authentication method chosen. with AD FS defaulting to a comparison=exact attribute.. As stated in the MSDN article Authentication Handler Overview, if the comparison attribute is set to “better”, “minimum”, or “maximum”, the method of authentication must be stronger than, at least as strong as, or no stronger than one of the specified authentication classes. This gives us some latitude for using it to invoke the desired authentication method through customization of the sign-in process. With SAML the authentication reference is encoded in the SAML request, and to access and to use the information therein, in order to relay the authentication request to our third-party IdP, we need to customize our sign-in process so that the incoming SAML (AuthnContextClassRef) request is decoded. The information we then need needs to be extrapolated so that we can then make the correct routing decision, sending the client to the correct provider. Examples provided on Codeplex hint at how this can be done, by assigning a authentication methods to a relying party using FBA and IWA.

On the other side, let’s look at an example using a WS-Federation based setup.

WS-Federation Passive Profile supported authentication methods

Authentication Method	Authentication Context (wauth) URI
Username/Password	urn:oasis:tc:SAML:1.0:am:password
Transport Layer Security (TLS) Client	urn:ietf:rfc:2246
Integrated Windows Authentication	urn:federation:authentication:windows

With the WS-Federation passive requester profile, the authentication type (wauth) parameter is specified in the query string of the browser or can be specified from the relying party application itself. The whr parameter is used to indicate the claims provide to use for logon.

MFA Step-Up Scenario

Let’s look at a step-up scenario using WS-Federation with an MFA provider.

In the above graphic, we have a third-party MFA provider handling the authentication requests for internal access.. I’ve not included the AD FS Proxy for external access, but should we wish to do so, we could adopt our AD FS proxy configuration and:

– remove the local authentication handlers from the <localAuthenticationTypes> section of web.config to ensure that MFA is always used in external access scenarios;

– follow the same methods used for internal authentication described below;

Internal access step-up scenarios imply the use of the default Integrated Windows Authentication (IWA) handler and the step-up mechanism. With a third-party multi-factor authentication provider, the (MFA) solution is configured within AD FS 2.0 as a claims provider. I’ll use the example of the WIF-based STS from PointSharp which I mentioned in previous posts.

In a step-up context, the STS needs to be able to process the required authentication request and pass this back to AD FS and the RP. With WS-Federation we can do this via the browser as a query string, or, from the web application make use of the wauth and whr parameters to set the authentication method.

Step-Up at the Relying Party Application

Using the WIF 3.5 SDK samples for our relying party, we modify the web.config to specify the desired authentication type. I’ve chosen the X509 certificate handler. For our WIF application this corresponds to an authentication method value of urn:ietf:rfc:2246

The homeRealm value is used to specify the claims provider we want to call for step-up, otherwise AD FS itself will attempt to handle the logon, treating as an authentication request for an x509 certificate.

On AD FS we configure the IP-STS as a claims provider.

On the IP-STS, we configure AD FS as a relying party

For convenience, both the STS and AD FS are sharing the same identity store (AD) and I’ve created a test user called demo in Active Directory and a security group called OTP, whom our user is a member of. We’ll use membership of that group on the PointSharp STS as a means of emitting an authentication method claim that corresponds to the expected authentication type. The claims value, urn:ietf:rfc:2246, is returned when a user logs on using MFA (e.g. OTP+password).

The user demo points their browser to the RP URL and with the web.config modifications, the access request is redirected to AD FS and then to the PointSharp STS as the Windows home realm (whr).

On the PointSharp STS during logon, the back-end PointSharp ID services handles the MFA logon request. At the initial prompt, the user enters their user ID and AD password:

They’re challenged to enter an OTP response (hardware/software token or SMS)

Once authenticated, the STS then processes the matching claims rules.

Above, demo is a member of the group OTP, as seen in the claims rule pattern, so a claims type of http://schemas/microsoft.com/ws/2008/06/identity/claims/authenticationmethod is generated. This is used to match the expected reply of the RP with a value urn:ietf:rfc:2246. and this claims is then passed back to AD FS.

In our test web app we see the appropriate authentication method and values being returned. No claims rules on the claims provider or relying parties (at this point) have been done.

Our MFA provider may also support multiple authentication types (AD password, SMS, tokens etc), so the fact that we logon at the STS is not necessarily indicative of a sufficient logon.With AD FS as the RP-STS, we can also block requests that don’t emit the correct authentication method at the STS on the relying party claims pipeline.

c:[Type == "http://schemas.microsoft.com/ws/2008/06/identity/claims/authenticationmethod", Value =~ "^(?i)http://schemas\.microsoft\.com/ws/2008/06/identity/authenticationmethod/tlsclient$"]
=> issue(Type = "http://schemas.microsoft.com/authorization/claims/permit", Value = "PermitUsersWithClaim");

With the authorization rule in place, another user, demo2, that is not a member of the OTP group, when accessing the RP, logs on at the PointSharp STS, but gets the following error at AD FS:

This translates in the event log to an access denied message:

The Federation Service could not authorize token issuance for caller ”. The caller is not authorized to request a token for the relying party ‘https://rp……..’. Please see event 501 with the same instance id for caller identity.

While we can block in this fashion, it makes more sense to enforce and evaluate a more fine-grained access at the application itself. If the app is intended as an internal-only application though, we can also block access from the AD FS proxy via an access rule.

exists([Type == "http://schemas.microsoft.com/2012/01/requestcontext/claims/x-ms-proxy”]) => issue(Type = “http://schemas.microsoft.com/authorization/claims/deny”, Value = “true”);

Step-Up within the Application

The previous steps described step-up at the web application (relying party), rather than within the application itself. The WIF 3.5/4.0 SDK provides samples for step-up authentication using an example of a low-value and a high-value resource within a given application. Here we’re leveraging step-up against a particular resource within an application.

Low-value resources are protected using normal Windows logon credentials (IWA), whereas high-level resources trigger step-up through the use of the certificate handler.

This allows us to add in step-up authentication within the application itself, according to the value of the resource.

A note on Virtual Smart Cards

I mentioned in the last post about virtual smart cards (or VSCs). As an authentication provider, they are available during Windows logon as a credential provider. Given that we wish to expressly enforce step-up at the application, then some sort of adjustment is equired. It may be possible to suppress the use of the VSC as a credential provider and make it available post-logon for application-only access, something that I’ve not tried, but one could argue that this is a case of the tail wagging the dog. We could also use an alternate account as described in Part I or disable single sign-on in the web.config on the AD FS farm to enforce logon between relying parties. The fact that we’re using IWA for normal logon masks somewhat the behaviour of revisiting the AD FS server when switching between IWA-based relying parties.

As ever, please extensively test before considering doing this sort of thing in a production environment.

Alternatives

What’s been discussed so far relates to solutions that are on the “direct” authentication path from an identity federation standpoint. There are also MFA solutions that involve indirect authentication using multi-factor authentication. When I refer to Indirect MFA, Í mean some other component outside of the federation logon process that handles the strong authentication aspects of logon. Diagrams always help to illustrate the cause Smile …

1. Via a non-federation capable proxy or gateway component. This component does not integrate with AD FS, but can provide an MFA capability. All connections to the RP are through the proxy. Post-logon, the proxy does some form of credential delegation to the back-end AD FS service. Here’s an example of a logon scenario with Forefront UAG 2010 on a non-federated trunk. While UAG does support federated trunks (as a relying party), MFA on a federated trunk is not (to my knowledge) possible unless we use an upstream claims provider.

2. Via an MFA web agent running on the ADFS proxy as an ISAPI filter or module. This follows the traditional web access management approach of logon via a web agent, with the filter intercepting the call. The user must logon using the stronger form of authentication before the web application, in this case the AD FS proxy pages are exposed. While functionally “integrated”, the two operate technologically independent of one another.

3. Via customization of the AD FS sign-in pages, allowing authentication to a MFA provider through web services. Of the three, this is (in my mind) is the most technically plausible, but handling step-up in such cases would also be complex and I’ll refer to that in a moment.

None of the above mechanisms are particularly well suited to step-up because the MFA logon process wraps around normal AD FS logon process, rather than integrating with it. While they may be valid in other access scenarios, i.e. the logon request is intercepted by a handler that doesn’t understand federated logon.

Option 3 is interesting as, via a slight modification, it supports illustrating where MFA is going in the next release of AD FS in Windows Server 2012 R2.

Windows Server 2012 R2

In AD FS R2, Microsoft are making available an MFA API for vendors to plug-in to and integrate with the federation service directly, allowing for a more rich logon experience. This also extends the concept of using multi-factor authentication not only at a protocol and application level, but at a policy level too, whereby policy per relying party for authentication is achievable. It also suggests that the redirect method via claims providers is being eschewed by Microsoft in favour of a more AD FS centric approach. I suspect the aim here is to provide a more level playing field for integrating external authentication providers with AD FS rather than placing the burden on the vendor and heavy use of customization to support scenarios described..

What this means for step-up scenarios we shall see. I’ll be looking at this raft of new features with AD FS R2 in future posts.

Virtual Smart Cards (VSC) and AD FS 2.0

July 6, 2013AD FS 2.0, Certificates, Claims-based Authentication, Multi-Factor Authentication, PKI, Window Server 2012, Windows 8AD FS 2.0, Certificate Services, Claims-based Authentication, MFA, Multi-Factor Authentication, PKI, Virtual Smartcard, VSC, Windows 8, Windows Server 2012mylo

Before I finish the second article on Step-Up Authentication, I thought I’d write something quick about Virtual Smart Cards (VSC), as they also feature in the next post.

While Windows 8 has been taking lots of flak for various UI changes, there are a number of nice new features that have snuck in rather quietly. One of these is support for Virtual Smart Cards (VSC). VSC’s provide an alternate strong authentication mechanism that removes the need for a physical smart card reader. They emulate the use of a physical card reader via the use of the Trusted Platform Module (TPM) found in most modern business-grade computers. The TPM module stores the private key of the virtual smart card. While, it’s not two-factor authentication per se, (the virtual smart card is stored on the same device as the crypto module), it is nonetheless an improvement strength-wise over username/password and software-based digital certificates. We’ll give it the official 1.5x times authentication moniker (1.5FA) Smile .

Private keys are stored in the crypto functionality of the Trusted Platform Module (TPM) of the laptop. The private key is device centric, with the virtual smartcard stored on the same computer. The TPM module needs to be enable on the computer. This can be done manually (woo-hoo!) or via some form of script, or in conjunction with vendor client instrumentation software.

VSCs provide a number of nice features, but they add a little more added complexity in the setup stakes. Given that we’re emulating physical smart card behaviour, we’re going to need a certificate and that means Certificate Services and an enterprise Public Key Infrastructure (PKI).

I’ve used a Windows 2008 R2 CA in this example. On the enterprise certification authority (CA) we can duplicate the built-in Smartcard Logon template found in certificate services using the V2 Windows Server 2003 compatible template.

With our new template, entitled Virtual Smart Card, on the Request Handling tab set the certificate purpose to Signature and Smart Card Logon and the minimum key size to 2048. On the Cryptography tab set the cryptographic provider to the Microsoft Base Smart Card Crypto Provider.

Give (authenticated) users Enrol permissions on the Security tab of the template and then issue the new certificate template.

We can use the built-in tool TPM Virtual Smart Card Manager (tpmvscmgr) to provision the smart card.

tpmvscmgr.exe create /name Auth360Test /adminkey random /generate

The generate command formats the TPM virtual smart card so it can be then used to enrol for certificates.

From a LAN or DirectAccess connected PC we can enrol via use the MMC Certificate Users snap-in, using the Request New Certificate option

Select the Virtual Smart Card template.

During enrolment a PIN needs to be set.

With the VSC enrolled. we can now logout and the virtual smart card should be available for logon.

Click on our enrolled user and then logon with our PIN.

I thought I’d give this a whirl with AD FS. For the purposes of this exercise, to support VSC smart logon, I changed my AD FS proxy configuration to support client certificate authentication, modifying the local authentication types parameter in the web.config on the AD FS proxy. We’ll cover other logon scenarios using VSCs in the next Step-Up authentication post.

Meanwhile, TLSClient (SSL Client Certificate) is elevated to the top of the list and switched with the default Forms authentication.

Users accessing the AD FS proxy with a VSC now get a prompt to select their certificate

Having highlighted and click my user, I now enter the PIN.

Users not possessing a ~~smart card~~ user certificate will get a 403 error.

The problem with this approach is that it’s a little generic. We’ve simply configured AD FS to authenticate users based on the presence of an X509 certificate.

We could always add our VSC users to a security group and reflect this in an authorization claim in AD FS, Even better we could configure authentication mechanism assurance and add an issuance policy to our virtual smart card template and then link that policy to a security group. Microsoft provide a couple of Powershell scripts to allow this, The Object Identifier (OID) of the certificate authenticating at AD FS needs to correspond to the linked claims rule to the OID in our “Virtual Smart Card Authentication” security group. We’ll look at this in a future post about Bring Your Own Device (BYOD), Workplace Join and Work Folders, new features in Windows 8.1.

Step-Up Authentication Scenarios with AD FS 2.0 Part I

May 17, 2013AD FS 2.0, Claims-based Authentication, OpenAM, SAML 2.0, SimpleSAMLphpAD FS 2.0, AuthnContextClassRef, ForceAuthn, OpenAM, SAML 2.0, Step-Up Authentication, Strong Authenticationmylo

This post refers to additional logon schemes that can be supported in AD FS by forcing users to re-authenticate or step-up/step-down authentication to federated web applications. It was prompted by a recent request from a customer :

“We wish to connect a SAML 2.0 Service Provider (SP) to AD FS. For security reasons, we require our internal users to logon (again) when connecting to this web application. All users connecting through the AD FS proxy should be prohibited access.”

Whether we choose to call this process re-authentication or step-up authentication really depends on the access case. To meet the requirement, we’ll be breaking single sign-on (SSO) when accessing the web application above by sending parameterised requests from the web application to AD FS, specifying how to handle authentication uniquely for this app.

Some folks may have pre-conceived ideas about what constitutes step-up, perhaps because it is often associated with multi-factor authentication. While the two do complement one another nicely, step-up is not necessarily multi-factor. Rather, use of step-up as an access mechanism, is governed by the strength of authentication we wish to accrue to access, at a level commensurate with requirements for protecting that resource. We can use weaker (single factor) authentication where this is deemed sufficient or appropriate. As an example, a customer may employ two-factor authentication on the outside/edge for all users and then elect to use the AD password, as an additional step-up mechanism for corporate users only to gain access to internal resources. In authentication strength terms, this is step-down authentication, but in functional terms, it’s designed as a step-up method.

I make the above point, because in the examples described here, we have users logging onto their workstations either using weak (username/password) or strong (two-factor) authenticating against other federated web applications with these credentials. In each case, we plan on forcing users to logon again when they access this particular SAML 2.0 web application to “step-up” security.

This is an internal only access scenario for the enterprise, meaning that users connecting via the AD FS Proxy should be denied access. Since AD FS Rollup 1, we’ve been able to specify Issuance Authorization Rule on the relying party (SAML 2.0 SP) pipeline that allows requests sourced from the AD FS Proxy to be identified and acted on via the claim description: http://schemas.microsoft.com/2012/01/requestcontext/claims/x-ms-proxy

Accordingly, we’ll create a deny Issuance Authorization Rule on our SAML web application so that users connecting through the proxy will be blocked.

exists([Type == “http://schemas.microsoft.com/2012/01/requestcontext/claims/x-ms-proxy”]) => issue(Type = “http://schemas.microsoft.com/authorization/claims/deny”, Value = “true”);

Sample Scenario

In a default AD FS farm setup, a domain-joined Windows machine internal user connects to the AD FS farm and authenticates via the Integrated Windows Authentication (IWA) handler using Kerberos/NTLM. To alter this behaviour, for a given application, and force the user to re-authenticate, we must ignore the existing session cookie.

With WS-Federation, we can do this at AD FS, via a smart link, by specifying the wauth parameter:

https://sts.mydomain.com/adfs/ls/?wa=wsignin1.0&wtrealm=https://rp.mydomain.com &wauth=urn:oasis:names:tc:SAML:1.0:am:password

For a relying party using the WS-Federation Passive Requester Profile (WS-PRP) we can also specify the request in the query string or within application code also via wauth.

This is a SAML 2.0-based use case though. As a backgrounder, I suggest reading about SAML Authentication Context Classes and Strengths with AD FS. Within the SAML 2.0 protocol, SAML service provider (SP) can emits certain values in the SAML request that ensures that the required authentication method from the SP is honoured by AD FS. From an SAML 2.0 protocol standpoint, this may be accomplished by:

Setting an Authentication Context Class Reference (AuthnContextClassRef) in the requested authentication context from the Service Provider;
Specifying the use of Force Authentication (ForceAuthn) in the request set to a value of true;
Use of a Comparison rule that is set to exact to expressly set the authentication method. Other settings are also possible (which AD FS supports) but are not covered in this post.

Let’s look at the farm-connected conventions mentioned above in a bit more detail.

Authentication Context Class Reference

In Windows SSO logon scenarios, the AD FS integrated handler uses the SAML AuthnContextClassRef of urn:federation:authentication:windows. On our SAML 2.0 web application, we’ll request a authentication context class reference of urn:oasis:names:tc:SAML:2.0:ac:classes:Password, so that the forms handler (in AD FS) is targeted as the desired authentication handler.

Force Authentication

The specification of ForceAuthn=true in the initial SAML request from the service provider specifies that the Identity Provider (IdP) should force re-authentication of the user, even if they possess a valid session with AD FS.

Comparison Rule

The SAML 2.0 protocol supports the use of a comparison rule to determine the level of precision to be accorded to the authentication request. If none is specified, AD FS will assume that the attribute is set to exact, meaning that authentication should conform exactly to the AuthnContextClassRef request and is passed to the appropriate handler.

Configuring Service Providers

I’ve used two examples here:

OpenAM
SimpleSAMLphp

I also planned on including Shibboleth, but hosed my configuration in the process, by reverting the wrong Snapshot of my VM during testing.. *cough*… sorry about that Smile

OpenAM

Using OpenAM as a SAML SP example, we’ll invoke SP-initiated sign-on through the spSSOInit.jsp page. In the query string we’re specifying the authentication context and the desired force authentication.

https://myapp.mydomain.com/openam/saml2/jsp/spSSOInit.jspmetaAlias=/acs/sp&realm=acs &ForceAuthn=true&AuthnContextClassRef=urn:oasis:names:tc:SAML:2.0:ac:classes:Password &idpEntityID= http://adfs.mydomain.com/adfs/services/trust&RelayState=https%3A%2F%2Fmyapp.mydomain.com%2Fopenam%2Fconsole

Note: The above syntax is valid but watch out for white spaces in the example above, not to mention your own domain name. I’ve added spaces to make the text more legible.

AD FS will parse the request based on the emboldened items in the query string and ask the user to re-authenticate via forms sign-in.

SimpleSAMLphp

In SimpleSAMLphp, we can set the necessary settings in the configuration file authsources.php, specifying the authentication context and force authentication requirement.

‘ForceAuthn’ => TRUE,
‘AuthnContextClassRef’ => ‘urn:oasis:names:tc:SAML:2.0:ac:classes:Password’,

Authentication Options

How we choose to implement our step-up/re-authentication component depends on the question of sufficiency and what is an acceptable method to choose. For this exercise, this could mean:

re-using the Windows logon identity (re-authenticate);
using an alternate identity from within the same AD forest (step-up);
using an alternate identity residing in a connected forest (step-up);
using an alternate authentication service; a third-party application that provides stronger forms of authentication

Option 1 – Re-Authentication

The simplest option sees the the user replaying their AD credentials, logging on again via the AD FS form, before gaining access to the web application. This is clearly not step-up and doesn’t afford any significant additional protection, , but may fulfil compliance/auditing requirements for access.

Advantages	Disadvantages
Simple (uses same identity)	Re-authentication not step-up authentication (same password policy)
Protects against inadvertent access to the application if the user is already logged on (e.g. where user fails to lock OS)	Security gain is nominal. Requires claims authorization rules on the relying party to differentiate between valid/invalid users.

Option 2 – Step-Up Same Forest (username/password)

Option 2 uses another set of credentials held within the same AD FS forest. Access to the SaaS application is limited to those users using these credentials (i.e. their “step-up” identity) and an authorization rule to supplement this.

Advantages	Disadvantages
Authentication is stepped using another identity besides the corporate logon	More complex. Requires additional identity to represent users (user management)
Supports use of stronger password policies on the second identity	Security gain is moderate. Same factor (username / password) for step-up identity
	Less user friendly (extra identity)
	Shared authentication sources between identities (no isolation)

Option 3 – Step-Up Connected Forest (username/password)

A more complex rendition of this using multiple forests with a single AD FS instance (Option 3):

In the above setup we have an account forest for our corporate users and a resource forest, where the AD FS server lives (with the AD FS application pool account running in the account forest). A one way forest trust between the two exists. In this option, the step-up identities reside in the resource forest.

Advantages	Disadvantages
Authentication is stepped using another identity besides the current logon	More complex. Requires additional identity / shadow account represented in the remote forest (user management)
Supports use of stronger password policies on the alternate identity	Security gain is moderate. Same factor (username/ password) for step-up identity
Shadow account can use same sAMAccountName in remote forest	Less user friendly (extra identity)
Greater isolation / independence of action from account forest (supports selective authentication)	More complex to manage

For Options 2 and 3, we can also provide further refinement by using AD fine-grained password policies to implement a stronger password policy / account lockout policy applicable to our web application, that exceeds the ordinary password policy levels used for for corporate AD users.

In all above cases, we should consider further restraining access by passing custom claims on the relying party, to assist in determining whether the user in question should have access.

From an AD FS standpoint, there are no configuration changes required in the cases described thus far. You may note, however, that I’ve not yet mentioned IdP-Initiated Sign-On methods. SHAME! Well, there’s a couple of reasons for this, by which I’ll conveniently recuse myself Smile with tongue out

Firstly, there a nice solution posted on CodePlex, that works similar to the actions described in this post, albeit by customizing the AD FS sign-in pages instead. It allows assigning the use of forms logon logic to relying parties and also covers IdP-Initiated Sign-On and WS-Federation. Relying parties registered to use the forms logon are registered in AD FS web.config file, thereby bound to the forms handler.
Also, some customers may be unwilling to modify their default AD FS setup because of a fear that it will throw them outside the realms of Microsoft support. However, if you do wish to support IdP-Initiated sign-on scenarios using the methods above (AuthnContextClassRef and ForceAuthn), then I’m afraid you don’t have much choice as customization of the code-behind page for idpinitiatedsignon.aspx.cs is required. Without these changes, sign-on, either via logintoRP or relaystate query parameters, will fail as the desired authentication context (AuthnContextClassRef) has not been set and is not passed by the IdP to the service provider. I used the following MSDN article as a reference to customize the idpinitiatedsignon.aspx.cs and then tested this using logintoRP parameter, with the query string example below.

https://adfs.mydomain.com/adfs/ls/IdpInitiatedSignon.aspx?logintorp=https:/app.mydomain.com/web1/&RequestedAuthenticationContext=urn:oasis: names:tc:SAML:2.0:ac:classes:Password&ForceAuthentication=true

In Part II, we’ll look at step-up options with stronger / multi-factor authentication methods (aka Option 4). See ya!

UAG 2010 and AD FS 2.0 updated articles

April 29, 2013AD FS 2.0, Claims-based Authentication, Forefront UAG, Kerberos, Sharepoint 2010AD FS 2.0, Forefront UAG, Kerberos, Sharepoint 2010mylo

Thanks for those folks who notified me that some of the 2010 articles on the blog have become corrupted. The two original posts have been lovingly restored after applying some TLC.

November 4th 2010 posting: AD FS – Inside and Outside

December 3rd 2010 posting: The Triumvirate – UAG 2010SP1, AD FS 2.0 and Kerberos

Cheers,

Mylo

Claims-based access with AD FS 2.0 and PointSharp Identity Federation

April 18, 2013AD FS 2.0, Claims-based Authentication, PointSharp, Strong AuthenticationAD FS 2.0, Claims-based Authentication, PointSharp, Strong Authenticationmylo

In previous articles we’ve looked at inter-op scenarios with AD FS using gateway solutions such as Juniper SA, Microsoft Forefront UAG 2010 and access management platforms such as OpenAM. In this post, we’ll look at using AD FS 2.x with a Windows Identity Federation (WIF)-based Security Token Service (STS) from PointSharp (www.pointsharp.com). This provides us with a broader authentication platform than AD FS from which to make access control decisions.

In a default configuration, AD FS 2.0 makes use of the local Active Directory as an authentication service. As administrators, we may also wish to further extend authentication options available to AD FS. A number of mechanisms are available, allowing us to hook into third-party authentication services.

via plug-ins/agents exposed through IIS, either on the AD FS Proxy/Farm to connect to other authentication providers;
customization/ coding sign-in pages to connect directly to authentication providers via web services or other custom methods;
through a federation trust to another provider, e.g. an IP-STS/IdP.

Option 1 is the traditional access management method, using non-federated agents/filters to wrap around IIS. This approach is often independent of AD FS. Option 2 involves customizing the logon process within AD FS, e.g. customizing forms-sign-in pages to hook into back-end web services APIs that the third-party authentication service may provide. Option 3 is the claims provider route using the federation trust model. PointSharp cater for all three solutions. However, I’ll concentrate on Option 3, using their Security Token service (STS) as a strong/two-factor authentication provider .

To highlight a working scenario, let’s set out some basic requirements:

External users, including corporate users, must connect through the third-party STS using various authentication types, according to the desired requirements:
- Two-factor authentication (hardware token, soft token or SMS)
- An alternate password credential store (non-AD)
- Credentials from the Corporate directory (e.g. AD)
Internal users, connected to the corporate LAN, should be able to connect to relying parties using their Windows logon credentials (Kerberos/NTLM).
Applications must support SAML or WS-Federation in an external facing scenario and IWA (Kerberos/NTLM) for internal users.
The solution should support claims-based access control to the federated web application according to the desired authentication method

The PointSharp Identity Federation component (STS) is a .NET / Windows Identity Federation (WIF) application. It services authentication requests by connecting to a core-access management application via web services.

In logon flow terms, an abridged view of the process is:

The external User connects to Relying Party Web Application
Browser redirect to AD FS Proxy. AD FS local authentication types are disabled. A claims provider is defined and the authentication request is passed to this.
Browser redirect to PointSharp Identity Federation STS. User logs on. Policy-based access control and claims processing is performed. SAML token is issued.
Browser redirect to AD FS (RP-STS). Perform claims processing on Claims Provider and Relying Party.
Browser redirect to Relying Party for authorization and access to application.

Users connect to the PointSharp Identity Federation claims provider (configured) via AD FS, to provide two-factor authentication for external access scenarios. In order to bypass the (in-built) AD claims provider for AD FS external access, whilst continuing to provide a Windows SSO experience to corporate users, we make a couple of configuration changes in AD FS proxy and farm nodes:

Disable all local authentication types on the AD FS Proxy to pass authentication requests to the PointSharp STS. This is done to bypass home realm discovery (HRD) mechanisms and remove the proxy as an authentication layer. We do this by removing the forms, basic and X509 authentication types within the web.config of the AD FS Proxy in the microsoft.identityServer.web section:

On the local AD FS farm we adjust settings to ensure that the default Active Directory claims provider, not the PointSharp claims provider, is used for authentication of users connecting via the internal/corporate network. We do so by customizing the homerealmdiscovery.aspx.cs on the AD FS farm to ensure that the AD claims provider is used for Windows logon. Refer to this blog article on how to accomplish this.

With the above changes, all logon requests via the AD FS proxy will now be handled by the PointSharp STS.

Before continuing further, let’s look at how the PointSharp Identity Federation component (STS) and the backend PointSharp authentication services work to support desired authentication types. To accomplish this, we’ll need to dig a little deeper into how identities are stored/used within the configuration.

Configuration Storage

As with the majority of Access Management (AM) solutions out there, it’s worthwhile pointing out the distinction between a store used for identity (read-only) lookup purposes, such as a user repository, versus the store the AM solution uses for holding (writing) configuration options concerning user/profile/preferences. Typically, configuration or data storage is represented in a single aggregate store where information about access identities is written. Conversely, user storage(s), may consist of multiple repositories, which we read user information from. PointSharp uses an LDAP store, e.g. AD LDS, AD or other LDAP v3 compliant servers for configuration/data storage. The store retains information concerning the users profile, the authentication methods used/supported, additional secrets etc. Sensitive information within the store is encrypted or (optionally) the entire storage container itself.

User Storage

In PointSharp lexicon, user storage is used to define an entry point within a repository for basing scoped searches/extractions from. We can then subsequently target items extracted for authentication/authorization processing. User storage may be one or many directories (AD/LDAP) or specific containers (organizational units) within one or many directories. Optionally, we may then target a desired authentication method against defined user storage types.

With a given user storage, via scoping options and the use of an LDAP filter , we define objects of “interest” in the storage and, at an attribute level, define various attributes, e.g. logon ID, to be used. This could be a security principal such as sAMAccountName, userPrincipalName or uid, subject to the object class. In the above screenshot, a User Storage called “inetOrgPerson” has been created, and within this store (AD), searches have been limited to include object classes of the inetOrgPerson type from given OUs. The (LDAP) search filter in the chosen user storage is:

(&({usernameAttribute}={username})(objectClass=inetOrgPerson)(objectCategory=person))

There’s some latitude here on what we may wish to include/exclude as objects of interest, for logon purposes, abstracted from the logon process normally associated to the native directory. For example, disabled accounts, which might sound bizarre, can also be exposed via user storage. Attributes such as UserAccountControl are available to expose/include in a scoped search within user storage, thereby allowing subsets of users for remote access, not normally available in a local authentication context to be used. We may wish to make these available purely for external access. In practical terms, imagine that we have a subset of users that we don’t want to be able to interactively logon to AD, from a domain-joined PC, yet should be able to logon externally (only) via our Identity Federation STS. Here’s an example of an LDAP scope that targets disabled users to be defined at a storage level.

(&(objectCategory=person)(objectClass=user)(userAccountControl:1.2.840.113556.1.4.803:=2))

User storages are processed iteratively. We can include a number of user storage types according to access needs and once we’ve defined them, identify the types of authentication we wish to use directly (via the storage) or indirectly through access policy.

Authentication Services

PointSharp, through back-end authentication services, provide authentication types available directly through listeners via web services or RADIUS, according to the access scenario. Since we’re dealing with identity federation here, this equates to web services. At this point, we can make available a given authentication type to be used in the identity federation process (e.g. SMS) or elect to use a more fine-grained policy-based authentication process. Smart Authentication (SmartAuth) refers to a policy-based / attribute-based access workflow executed during logon. Through these policies the authentication type to use for a connecting user is determined. This allows for more granular authentication flows to meet requirements. Moreover, this can also be further refined at the (front-end) Identity Federation component (STS) via claims-based access control.

Using the user storage concepts, let’s have a look at two identity federation scenarios. The first is a “basic” approach using the default Active Directory, available as a user store for moderating external access.

Basic Scenario (Single Storage)

In the above setup, we’re “scoping” our storage based around using various OU’s within AD. The first storage uses sAMAccountName for internal users using their Windows logon ID, the second uses userPrincipalName (UPN) for external users. In this example, sAMAccountName is analogous to EmployeeID and userPrincipalName to the emailaddress of the external user. Each respective set of identities live within their own OU’s within Active Directory.

Complex Scenario (Multiple Storage)

Similar to the basic setup, we’re also scoping our user storage at OUs within a given store. In this case we’re also adding additional repositories, such as a Partner/Affiliates store (e.g. Extranet), to pull in their identities for usage in logon scenarios ….

With the user storages defined, we then define individual authentication types within the back-end PointSharp authentication service and expose these as individual listeners, invoked directly by the caller. In our case, this is the PointSharp Identity Federatrion component calling a smart authentication rule. to adopt more fine grained authentication decisions at logon.

In the above policy, I’ve elected to use membership of a Windows group (in user stores) to target required authentication types. This involves static management of a group, so it may be less desirable than using something like a UPN or Email address, matched against a particular suffix to offer a more dynamic evaluation.

For example, a dynamic evaluation can be used, as in the above example, to attach an authentication method to users with an @auth360.net UPN suffix to use an OATH token. I’ll cover dynamic evaluation using directed authentication types and responses in a later post.

With PointSharp Identity Federation, we specify the use of a smart authentication rule as the authentication method

Users logging on from a relying party externally are redirected to the PointSharp STS. (Note: I’ve already setup the PointSharp STS up as a claims provider within AD FS).

Within the PointSharp authentication service, if you recall from the earlier MemberOf smart rule graphic, we’ve identified four authentication types: OATH, SMS, PointSharp Password and AD Password. OATH tokens are event or time-based OTP schemes using hardware, software and SMS-based logon mechanisms. Both support (optional) challenge/response password/OTP combinations from the user repositories and the login process adapts to this according to the rules defined with the PointSharp authentication service. In addition, the PointSharp Password is an alternate login credential that can be called upon and is used in cases where customers do not wish to employ two-factor authentication, nor expose the AD password to external access. Instead, they wish to use a separate password source, independent of AD, with separate password/lockout policies, that can be used to provide claims-based access via the PointSharp STS to their web applications. Should we also we wish to make AD password-access available as a possible authentication type, this is also included in the example. Remote lockout conventions can also be applied to AD users, independent of the AD password policy, to ensure that remote access lockout does not necessarily incur a AD password lockout, and to prevent Denial of Service (DoS) lockout on a given user.

Within the PointSharp authentication service admin UI, in a storage called AUTH360, four users have been created for testing:

oathman is a user using an OATH token (hardware token / soft token)
smsboy is a user using an SMS authentication method
psidgal is a user using a PointSharp password
adkid is a user using an AD password

From within PointSharp Identity Federation (STS ) we can define claims-based access rules to be passed onto AD FS. To accomplish this, we create custom claims rules on the STS that conform to the authentication type we desire. This is then injected in the SAML token and consumed as a claim by AD FS, as the RP-STS, for further processing, and passed on to the RP. For example, the four authentication types defined within the SmartAuth rule are now processed at the STS :

These are passed back via the custom claims definition:

http://schemas.auth360.net/ws/2008/06/identity/claims/access

On AD FS, we create a claims description that conforms to the above description

On the PointSharp Identity Federation claims provider, we pass the above claims as well as any additional claims that we also elect to emit. On the claims provider pipeline in AD FS, we configure Acceptance Transform rules to pass the Access Type claims and any other rules that the Claims Provider STS has made available:

On the relying party application we define our issuance transform rules.

I’m using SimpleSAMLphp, a SAML 2.0 Service Provider, as my Relying Party. AD FS, as a broker, provides the necessary bridging between the WS-Federation passive STS of PointSharp and, in this case our SAML 2.0 RP. In the “groups” claim we pass an inbound custom customs claims definition that transforms the authentication method http://schemas.auth360.net/ws/2008/06/identity/claims/access and emit this as a SAML attribute that SimpleSAMLphp can then consume:

c:[Type == http://schemas.auth360.net/ws/2008/06/identity/claims/access] => issue(Type = “groups”, Issuer = c.Issuer, OriginalIssuer = c.OriginalIssuer, Value = c.Value, ValueType = c.ValueType);

I’ve setup up a basic “Hello World” PHP application, which calls the SimpleSAMLphp libraries and then display the processed attributes in the web page. In our example, the access type (and authentication type) is expressed via the groups SAML assertion in array [0] –LOA4-AD. This is a user logging on who is a member of group LOA4-AD (using AD credentials).

Array
(
    [groups] => Array
        (
            [0] => LOA4-AD
            [1] => users
            [2] => members
        )

    [http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn] => Array
        (
            [0] => adkid@auth360.net
        )

)

At the relying party, we’re now at liberty to make authorization decisions based on the incoming claim, according to the strength of the authentication type. I’m using SimpleSAMLphp here as an example, but the same conventions can be applied to other WIF-based RPs/STS such as SharePoint.

In a future post, I’ll look at more refined policy assessments using access based on dynamic evaluation and SAML authentication contexts such as SAML AuthNContextClassRef and WS-Fed AuthenticationMethod in RP/SP initiated-sign-on scenarios. Meanwhile, I hope you enjoyed the post.

Exchange 2010 OWA, Claims-based Authentication and AD FS

January 11, 2013AD FS 2.0, Claims-based Authentication, Exchange Server 2010mylo

I was asked recently whether it was possible to use Outlook Web App with AD FS 2.0 for authentication. I’d toyed with this in the past with Exchange 2010 SP1, but things had changed in the Exchange mechanics (.NET) since then and this had caused problems for me when using the old configuration with later service packs. I was curious to see how it would work with Exchange 2010 SP3. Fortunately, it’s always nice to find someone who has dug before you and the following article provided a good guide :

http://allmsft.blogspot.be/2012/02/owa-sp2-and-adfs.html

Courtesy of a few adjustments to the author’s notes, which I’ll describe here, it shouldn’t be too long before, it’s possible to have OWA up and running using AD FS and claims on a test rig.

Let’s assume the initial steps as described in the article have been followed:

a new IIS web site has been created
OWA virtual directories have been created in Powerscript
FedUtil has been run

We will need to tweak the web.config of the OWA application and you need to watch for case sensitivity issues with the configuration. Equally, the nuances of FedUtil and how it processes the web.config file can also be a problem. Changes are required in different portions of the file. In the <modules> section of the OWA web.config, the following needs to be add to the header (follow the case exactly):

I also found during the FedUtil processing that the above line would often be rejected, with a complaint about System.WebServer tags. Should you experience the same issue, try setting the remaining configuration changes without setting the module change above, get FedUtil to accept them and then change the web.config once more, in order for FedUtil to reprocess and accept the value.

Note that you’ll need to add the securityTokenHandlers after the AudienceURI section.

When creating the Relying Party in AD FS and pointing to the metadata path in the browser, you might it failing. In my case, testing the federation metadata would redirect the browser to AD FS, because the published metadata fell under the /owa virtual path and the control of the federation service handler. Creating a virtual directory that pointed directly to the owa\FederationMetadata folder under the web site rectified this.

You’ll need to specify the /owa path in the browser when accessing the OWA claims website, otherwise you’ll get an error within OWA, something along the lines of:

An unexpected error occurred and your request couldn’t be handled.

Copy error details to clipboard

Show details

I suspect this is down to the requested URL not matching the Relying Party Identifier.

Normally when I finish this posts, there’s always a warning about testing…. in this case, this is particularly so. It looks like this is not an extensively tested solution with the Exchange team and that aspects such as Claims to Windows Token Service (C2WTS), while acceptable in the SharePoint world, have not translated to real-world acceptance with the Exchange platform.

So… TEST, TEST,TEST and Caveat Emptor.

AD FS 2.0 Rollup 2 and WHR – We Has Resolution (Part 2)

December 12, 2012AD FS 2.0, Claims-based AuthenticationAD FS 2.0, Home Realm Discovery, WS-Federationmylo

In the previous post we covered WS-Federation whr changes in AD FS 2.0 Rollup 2. With this fix in place and enablewhrpersistence set in our web.config, let’s look at scenarios on how the configuration can be used to manipulate home realm discovery in greater detail.

Our mythical ‘Foo’ organization consists of an existing AD FS 2.0 proxy/farm setup and two claims providers configured:

default AD provider
third-party claims provider providing strong/two-factor authentication (2FA) to Foo users

Foo has recently engaged in a number of collaboration projects with three other companies: Fee, Fie and Foe. Wishing to further cement these relationships, Foo has elected to setup federation trusts with each of them, and provide access to their local WS-Federation web applications. The Foo Security Officer, however, has decided that other home realms should not be visible within AD FS in the drop-down box of the home realm discovery page. All RP-initiated requests via the AD FS proxy must go to their third-party two-factor authentication (2FA) claims provider. This requirement, however, conflicts with the need to service federated logon for other organizations.

Given the above constraint, we have a number of options:

Use an additional farm;
Customize the home-realm discovery pages and logon experience on the existing farm to support the desired user experience for third-parties;
Customize the relying party(s) to route the whr request;
Use out-of-the-box features.

Not being much of a code monkey, let’s look at options out-of-the-box. With the new configuration, there are now five claims providers Foo has to deal with.

Active Directory Claims Provider (0)
2FA Claims Provider (1)
The Fee Organization Claims Provider (2)
The Fie Organization Claims Provider (3)
The Foe Organization Claims Provider (4)

Foo AD FS Proxy Customization

For external access, as per security requirements, only the 2FA claims provider should be visible directly from the proxy, making it the default selection for external access. This is arranged on the AD FS Proxy side by modifying the homerealmdiscovery.aspx.cs file and then removing the claims providers, as eligible entries, from the Page_Init section of the file. We need to process their removal in reverse order, starting with the last claims provider in the list, then the next to last etc., until we have the desired CP . For example, with five claims providers, the following changes are made:

PassiveIdentityProvidersDropDownList.Items.RemoveAt(4);
PassiveIdentityProvidersDropDownList.Items.RemoveAt(3);
PassiveIdentityProvidersDropDownList.Items.RemoveAt(2);
PassiveIdentityProvidersDropDownList.Items.RemoveAt(0);

We’re left with claims provider (1) in this example, the 2FA provider. Note the order may vary according to order created.

Once this has been done, the following line also needs to be added :

SelectHomeRealm( PassiveIdentityProvidersDropDownList.SelectedItem.Value );

This will default logon to the 2FA provider claims provider at the AD FS proxy.

Foo AD FS Farm Customization

For users with managed clients/corporate PCs in the Foo organization, we need to ensure that realm discovery is also handled in the right manner. 2FA is not a requirement internally, but SSO via the Windows logon token is desirable. While we covered this in a previous post, it’s worth repeating here. On the AD FS Farm, the Page_Init section of the homerealmdiscovery.aspx.cs file needs to be set so that it defaults realm selection to the Active Directory claims provider.

SelectHomeRealm ( PassiveIdentityProvidersDropDownList.SelectedItem.Value );

If this is not set, then all claims providers are visible on the home realm discovery page, something which we don’t want to trouble internal users with on the corporate network.

With persistence enabled on the home realm discovery page (of the Proxy), a user may fall foul of cookie handling if he/she works from home, logs on and then returns to work, only to discover that the cookie has persisted and the browser points them to the 2FA provider. We can temper the cookie behaviour of the AD FS proxy by disabling persistence within the web.config on the AD FS farm.

Connecting Organizations

For users from other organizations connecting to Foo; e.g. Fee, Fie and Foe, we rely on smart links from AD FS instances in these organizations to route the request and for the home realm cookie to be written correctly via the whr parameter. Note that these claims providers could also use non-Microsoft identity providers/issuers, such as a Juniper SA (SAML) or a PointSharp WS-Federation Identity Provider, such as .

While useful, smartlinks are not without limitations. Firstly, we’re assuming the relying party is a WS-Federation based web application. If the relying party is a SAML 2.0 web application then the WS-this approach is not applicable. The solution described here does not work and a different type of customization is required. More on this in a future post. The second limitation concerns users from claims provider realms bookmarking Foo (federated) web applications. Should the home realm cookie expire, accessing a bookmarked RP web application will fail as it routes them to the 2FA provider. While Rollup 2 made persistence via whr possible, we need to workaround this shortcoming. We could set the lifetimeInDays value of the cookie in the homerealmdiscovery.aspx.cs of the Foo Proxy to such a high value that this would not be an issue. Sadly, this is not entirely foolproof either. Browser configuration for users in partner organizations, e.g. Delete browsing history on exit, may influence whether the realm cookies are retained or not. Whatever setting is opted for by the resource organization (Foo) is something that will need to be communicated with partner organizations.

Federated SSO Logon with AD FS 2.0 in an Extranet with UAG

June 25, 2011AD FS 2.0, Claims-based Authentication, Forefront UAG, Sharepoint 2010AD FS 2.0, Claims-based Authentication, Forefront UAGmylo

This is one of those “what if?” scenarios with AD FS 2.0 which arose at a customer recently: they wanted to provide secure logon to users in an Extranet Active Directory to web resources in their corporate Active Directory (e.g. Sharepoint). In a pure AD setup, with no third-party SSO products involved, this sort of thing has often been accomplished in the past through the use of a forest trust between extranet and corporate forests. This approach, however, tends to make network and security departments unhappy; with all sorts of firewall ports needing to be opened, making swiss cheese of interior firewalls. With Windows 2008 R2, we can also do this sort of thing by configuring an Extranet AD FS 2.0 instance(s) in the DMZ (limiting firewall traffic to HTTPS only) and then establishing a federation (claims provider) trust between the corporate AD FS and the Extranet. This is similar to the partner or federated SSO scenarios that Microsoft describe in their documentation. In this scenario, the Extranet AD FS instance is analogous to the Account Federation Partner and the corporate AD FS instance to the Resource Federation Partner.

To make this process more interesting (life is never dull), it was suggested we put a UAG in the Extranet (in place of the AD FS Proxy) to support strong/two-factor authentication requirements. This meant that some form of jiggery-pokery with Kerberos Constrained Delegation would be required between the Extranet UAG instance and the Extranet AD FS farm, to ensure that groovy Web SSO experience was maintained all the way to the target web application.

Components

Forefront UAG 2010 SP1 (extranet.mydomain.com)
Extranet AD FS (extranet.mydomain.com)
Forefront TMG 2010 SP1 (sts.mydomain.com)
Corporate AD FS Proxy (sts.mydomain.com)
Corporate AD FS Farm (sts.mydomain.com)
Sharepoint 2010 Farm (sharepoint.mydomain.com

So we have two zones bridged by an AD FS federation trust: an Extranet Zone and a Corporate Zone.

The above is how I configured the sandpit for testing. Our example web application (Sharepoint), is configured as a claims-aware application and the client has bookmarked it as a favourite. He/she is able to link to the Sharepoint site (sharepoint.mydomain.com) directly and this is where the authentication process kicks in. Walking through the process.

1. The client accesses the Sharepoint URL (https://sharepoint.mydomain.com). (reverse proxied through TMG). The Sharepoint web application is configured as a claims-aware web application with the Corporate AD FS 2.0 farm configured as its SP_TrustedIdentityTokenIssuer using e-mail address as the primary claim.

2. The Sharepoint 2010 security token service (STS), a relying party of the corporate AD FS 2.0 instance, redirects the client to the corporate AD FS 2.0 farm. The client is connecting from the Internet, meaning that the fully qualified domain name sts.mydomain.com (for AD FS) on the Internet resolves to a public IP address, namely that of the AD FS Proxy. The client is redirected to the proxy.

3. The corporate AD FS, with the proxy as arbiter for the AD FS farm, possesses two claims providers: the default corporate Active Directory and a claims provider trust setup to point to the Extranet AD FS instance (Partners and Affiliates in the graphic). AD FS itself cannot determine which realm the client belongs to, so when the client connects he/she home realm discovery (HRD) is performed and the client must choose between selecting the corporate or Extranet realm (this process can be automated… we’ll cover this in a later post). As a result of Home Realm Discovery, the client is thereby redirected to the services endpoint for the Extranet AD FS. In this scenario, this translates to the public IP address of the UAG trunk.

4. With the client redirected to the UAG for logon, the UAG server(s) processes the logon request. In this example, UAG is configured to use RADIUS for authentication. This is because we’ve opted for strong authentication (using tokens). RADIUS is being used to bridge the connection between UAG (as a RADIUS client), and the strong authentication provider. The token is submitted via an application running on a smartphone and the client enters the One-Time-Password (OTP) and PIN via the UAG form (4a). The credentials are forwarded by UAG to the RADIUS server (4b) running on the OTP provider. In this example, the user repository for the one-time password is also the Extranet AD (4c), accessed via LDAP. The UAG server(s) are also domain members within the Extranet AD. Once the OTP logon process is complete, we can chain the logon process to perform federated back-end authentication to the Extranet AD FS instance(s), obtain a kerberos ticket from the Token Service using Kerberos Constrained Delegation (KCD). This is possible because the UAG server(s) is trusted for delegation by the AD FS server(s). This process is described in a previous blog post (Federated Identities with UAG 2010 SP1 and Office 365). On the Extranet AD FS, the Corporate AD FS instance is configured as a relying party. We extract the e-mail address from the AD (Send LDAP Attributes as Claims), providing this information to the relying party in a pass-thru rule (issuance transform rules) .

5. When authentication is complete at the Extranet AD FS, an HTTP POST by the client is submitted to the corporate AD FS Passive Federation Endpoint. The Corporate AD FS, acting now as an FP STS, processes the claim according to acceptance transform rules configured (pass thru e-mail), before handing over to the relying party where the issue transform rules are then processed (pass thru e-mail address).

6. The client is then redirected the Sharepoint web application, the e-mail address claim is processed by the Sharepoint STS, and they gain access to the Sharepoint site.

Extranet UAG Configuration

To make this configuration work on the Extranet UAG side, we have to ensure that the federated logon process is not interrupted or interfered with. At the same time we still have to deal with the strong authentication requirement. As stipulated in previous posts, with non-federated trunk authentication we can satisfy both strong authentication requirements and federated logon to the local (Extranet) AD FS instance. This time, however, the resource lives in the corporate realm. UAG is not directly responsible for proxying connections to the Sharepoint web application. Nonetheless, there are some unusual requirements.

On the Extranet UAG, there are three authentication providers configured:

RADIUS/OTP Server
Extranet Active Directory Domain Controller (can be used for Authorization by the RADIUS server)
Extranet Active Directory Federation Services (AD FS)

The AD server is optional should you wish to use AD-based authorization groups with the RADIUs authentication server. The AD FS 2.0 server is required for the Extranet federated logon piece.

Surprisingly, there are also two web application templates that need defining:

A Sharepoint 2010 web application using the Sharepoint 2010 template with the URL of https://sharepoint.mydomain.com
An AD FS 2.0 web application using the AD FS 2.0 template with the URL of the Corporate AD FS instance of https://sts.mydomain.com

Each of these web applications are configured to use the Extranet AD FS server as their authentication server. Without these web applications being defined, the login process fails at the UAG with a “request was unable to reply to an HTTP 401 request from application AD FS” being logged within the UAG Web Monitor. This one had be stumped for a while as UAG is not responsible for proxying traffic to the corporate AD FS proxy or the Sharepoint web application. I can only surmise at the moment this is done to the fact that UAG assumes the web application is behind it and therefore a corresponding application must exist.

I’ve mapped the logon process out in Visio.

If I have the time, I’ll deep-dive the entire setup in a later post. If this would be of interest to anyone, please let me know.

Mylo

UPDATE 28/06: Microsoft have updated their documentation describing partner access using federated claims to Sharepoint 2010.
http://technet.microsoft.com/en-us/library/hh285675.aspx

O365 and TMG with Strong Authentication (Part II)

June 2, 2011AD FS 2.0, Claims-based Authentication, Forefront TMG, Office 365mylo

Using TMG as a strong-authentication capable proxy for passive O365 clients and reverse proxy for rich/active clients

In the previous post I looked at configuring TMG to allow it to support both strong authentication of Office 365 (passive) web clients and at the time act as a reverse proxy for rich/active clients that use classical username/password for authentication.

Attached is a diagram highlighting the high-level communication flows associated with the previous post. I’ve emphasised the HTTPS traffic between the Federation Gateway and TMG for rich/active clients (the thick arrow), as it’s bi-directional in nature.

Unlike the passive client where all communication occurs through HTTP redirects, rich/active clients bounce around from server to server. This makes building a solution that supports multiple (strong/weak) authentication schemes difficult to implement and why, in the long term, customisation of the AD FS proxy pages may be the easiest route.

O365 and TMG with Strong Authentication (Part I)

June 2, 2011AD FS 2.0, Claims-based Authentication, Forefront TMG, Office 365AD FS 2.0, Forefront TMG, Office 365, Strong Authenticationmylo

This post looks at how TMG 2010 may occupy a role of hybrid AD FS Proxy for Office 365.

In previous posts on this blog we looked at using TMG as an AD FS 2.0 proxy .. When testing this back in Q4 2010, there was some uncertainty when testing (at least on my part), as to whether TMG as an AD FS proxy replacement was actually a supported configuration. Happily, it looks like these questions have been answered. In TechEd in Atlanta, the Office 365 deck on Identity and Access Solutions (OSP215) describes TMG as an alternative proxy offering for Office 365.

Here TMG substitutes the role of the AD FS proxy for corporate users using identity federation, with it being responsible for authentication of browser traffic (passive clients) coming from the Internet and traffic from Microsoft (active/MEX clients). One of the things about TMG is its flexibility and versatility. This was borne out in testing and it’s possible to support multiple flavours of access through a single web listener. For example, let’s say we need to support strong authentication for external / Internet-based clients using OWA 365 and Sharepoint 365, whilst at the same time we support internal/external users with rich clients, using conventional username and passwords, running Outlook and Lync. Let’s list those again:

Single factor (username/password) authentication for rich/active clients inside/outside the corporate environment… covering ActiveSync access from the outside, Outlook 200x from the inside/outside and MEX clients, such as Lync 2010 inside/outside
Single-factor authentication (username/password) for passive clients inside the corporate environment (OWA/Sharepoint)
Two factor authentication (2FA) for passive clients outside the corporate boundary (OWA/Sharepoint)

Inside the organisation, passive clients make use of the local AD FS 2.0 instance (rather than TMG), whereas Rich/Active clients use a more complex process . In fact, the latter makes for an interesting challenge, for any would-be admin, as the Microsoft Federation Gateway needs to call-back to the on-premise AD FS instance. Normally speaking, active and rich clients must, therefore, go through the AD FS Proxy for logon. In this post, we substitute the AD FS Proxy role for TMG, so that we may leverage capability that TMG can offer (I’m using the example of strong authentication).

The key to making this approach work with TMG lies in creating multiple web publishing rules, each with their own authentication requirements, using a single web listener. In doing so, we:

Create a web publishing rule that allows direct communication to the AD FS back-end for active and rich clients (effectively anonymizing authentication on the listener for the published paths in question)
Create a web publishing rule that triggers authentication (two-factor) on the TMG front-end and then uses delegation to the AD FS back-end using Negotiate authentication.

We are then able to support access requirements for both two-factor (external) logon from the browser, whilst also supporting the ability of single factor logon for active/rich clients, domain-joined and non-domain joined……..

There are a couple of tweaks in the TMG configuration necessary to ensure compatibility with AD FS 2.0…..

Disable Verify Normalization on the HTTP Filtering tab of each publishing rule
Disable Block High-Bit Characters on the HTTP Filtering tab of each publishing rule
Disable Link Translation on each publishing rule

Also, please ensure that:

DNS records for the AD FS Proxy point to the TMG web listener
A SAN or wildcard certificate is installed on the TMG listener with the appropriate FQDNs for the AD FS Federation Service endpoint (hint: export the certificate plus private key from AD FS and import into TMG)
Kerberos Delegation is configured for the AD FS Farm Application Pool Account or ADFS Computer Account (if the AD FS server is a single machine)

We create two publishing rules with the public name matching that of our AD FS 2.0 server/farm, sts.mydomain.com. :

Rule	Authentication Delegation	Paths	Users
#1	Kerberos Constrained Delegation	/adfs/ls/*	All Authenticated Users
#2	No delegation, but client may authenticate directly	/adfs/services/trust/2005/usernamemixed//adfs/services/trust/mex/	All Users

Rule #1 applies for the passive clients doing two-factor authentication on the web listener
Rule #2 applies for the rich/MEX and Active client profiles for Lync and ActiveSync/Outlook respectively.

The more restrictive rule (two-factor) should be applied first in the firewall list. As a general rule of thumb, let the TMG Logs and Reports tracker, together with Fiddler, help debug any protocol issues that may arise.

Next stop ….. UAG !!!!

(FOOT) NOTES

According to official documentation, Office 365 strong authentication scenarios include:

Two-factor authentication at Windows/Domain Logon
Two-factor authentication via Forefront UAG 2010 SP1 for web applications
Two-factor authentication via customized AD FS Proxy sign-in pages

If you have a fully-fledged public key infrastructure with smart cards, then you’re probably wondering what the fuss is about 😉

Option 2 looks promising.. However, after testing it and then reading and then re-reading the Office documentation, it appears that the working two-factor scenarios are limited to passive clients only (OWA/Sharepoint) and that Outlook and ActiveSync (O365) are not supported via UAG. Because a UAG server doing 2FA is acting as non-federated trunk, rich/active clients get stumped during authentication. Now, this may be possible to get working with some tweaking but it looks like some sacrifices would be required (e.g. disabling access policies on the trunk). I’m hoping I’m missing something here and some bright spark will put me right, part the clouds and show how it can be done Smile

Option 3 is very much possible if you’re prepared to roll up your sleeves and do some sort of customization of the ADFS Proxy sign-in pages to support 2FA, with your strong authentication vendor of choice. I’d expect to see some sort of progress from MS on this, given that Office 365 launches this month.

Getting this working through TMG was really the motivation for me here. If, as a prospective Office 365 customer, you have a requirement for strong authentication for external users, whilst at the same time you need to support traditional username/password logon internally, then maybe this option can assist..… as ever, your mileage may vary and please don’t deploy before testing this to death in anything close to production!

Adding multiple claims-aware web applications to a Sharepoint 2010 Farm.

March 28, 2011AD FS 2.0, Claims-based Authentication, Sharepoint 2010mylo

This is more of a mental note to self (and something which I kept forgetting the correct syntax for, despite using it in the past)… How to add an additional claims-aware web application to an existing Sharepoint 2010 farm.

$ap=Get-SPTrustedIdentityTokenIssuer
$uri = new-object System.Uri(“https://www.mydomain.com“)
$ap.ProviderRealms.Add($uri, “urn:sharepoint:mydomain”)
$ap.Update()

The original post courtesy of Steve Peschka:

http://blogs.technet.com/b/speschka/archive/2010/04/27/how-to-create-multiple-claims-auth-web-apps-in-a-single-sharepoint-2010-farm.aspx

The Triumvirate: UAG 2010SP1, AD FS 2.0 and Kerberos

December 3, 2010AD FS 2.0, Claims-based Authentication, Forefront UAG, Kerberos, Sharepoint 2010AD FS 2.0, Kerberos, Sharepoint 2010, UAGmylo

29/04/2013: I received feedback from readers that this original article had become corrupted, so I’m reposting it.

In the previous post I was looking at how to configure AD FS 2.0 with UAG 2010 SP1 RC and publishing Sharepoint through it in a straight claims-based authentication access scenario. This time we’re going to mix authentication protocols. As ever, do this in a test environment/sandpit, where a wrong move might not necessarily be your last Smile

Back in Q4 2006/Q1 2007, Stefaan Pouseele, an ISA Server MVP, helped out when I was trying a few access scenarios using ISA 2006, RADIUS and Constrained Delegation. He had been blogging about the concept of using a cheap RADIUS OTP solution with ISA and RADIUS. The gist of the solution was that it was possible to authenticate against a user database in the DMZ through RADIUS and then ISA’ support for kerberos constrained delegation to provide access to resources within the corporate Active Directory domain by using corresponding shadow user accounts. At the time I tested this out using ISA, RADIUS and Exchange and it worked a treat.

Here is the link to his original article:

The advantages were:

pre-authentication at the listener
perform regex expressions in RADIUS to strip/modifying incoming request
user lockouts occur on the remote DMZ user database, not the corporate Active Directory user ID
use smartcard for logon checkbox on the “shadow” domain user account to set automatic long passwords on the user; useful, if 3rd party IDSs need to be created for partners who don’t need AD logon credentials
reduce “surface area” of risk should theft of the device occur (e.g. Windows Mobile Smartphone)

There were downsides.. someone had to manage the DMZ ID’s .. shadows accounts had to be created on a 1-to-1 basis, doubling the management overhead. Nonetheless, it worked pretty well at the time with Exchange ActiveSync and mobile devices.

Roll on 4 years ago and testing with UAG 2010 SP1 reminded me of those earlier ISA scenarios. This time, however, the participants are UAG 2010 SP1, AD FS 2.0 and Sharepoint 2010. We’re still doing front-end authentication (this time with claims) and now transitioning kerberos to the back-end Sharepoint web app.

Objective

This post describes publishing applications through the Forefront Unified Access Gateway (UAG) 2010 SP1 using claims-based trunk authentication at the front-end and Kerboros Version 5 at the back-end. In this setup, a user will logon via AD FS and the UAG will then request a Kerberos ticket on behalf of the user and use that ticket to authenticate to the published kerberized application.

AD FS in this setup is our UAG trunk authentication provider. Our test web application in this case is a Sharepoint 2010 web application, with the application configured to do Negotiate (Kerberos) authentication.

The UAG SP1 documentation describes the broad process of what needs to occur but focuses primarily on using shadow accounts for federated logon (with a 3rd party). I’ll look at this approach in a later post. Initially, I was more curious as to see how this would work against a native local AD directory using “corporate” AD credentials for AD FS to parse at logon and UAG delegating those credentials via Kerberos to a web application.

We’re mixing and matching authentication here, using claims-based authentication at the edge, and then Kerberos as an enterprise protocol for authenticating to our web application, i.e. UAG is federation-aware but SharePoint is not. This is pretty cool. It means that AD FS can be used to handle Web SSO, whilst leveraging UAG to provide connectivity to applications using delegated credentials (in this case Kerberos).

System Setup

This is what was used in the “sandpit”.

UAG 2010 SP1 RC
AD FS 2.0 RTW
AD FS 2.0 Proxy
Sharepoint 2010 Web Application
Local Active Directory of which all the above are domain members (except the AD FS Proxy)

The AD FS 2.0 Proxy might appear surplus to requirements. You could for example turn on Forms-Based Authentication in the web.config of the AD FS farm, but in my test sandpit the application is configured for Integrated Windows Authentication (IWA) to test local AD SSO. The proxy, by definition, will do forms-based authentication and therefore fits the profile for claims-based trunk authentication via UAG.

External DNS Settings

portal.mydomain.com : 192.168.100.1
teams.mydomain.com : 192.168.100.1
sts.mydomain.com : 192.168.100.1

UAG is, in effect, in-line for processing of all traffic. So, when a user points their browser to https://teams.mydomain.com, the UAG intercept the request, does the necessary access/compliance checking, before the trunk handles the claims-based authentication logon process and redirect to AD FS (UAG is a relying party within AD FS).

If multiple claims providers are configured (as in this sample), then Home Realm Discovery (HRD) in AD FS may kick-in and the user selects the appropriate home realm for logon. In this test, I’m using the local “corporate” Active Directory for authentication. In subsequent blogs, I’ll extend this out to a federated trust (3^rd party or Extranet AD / AD FS instance).

Having selected the corporate realm, let’s logon with our test user 280368.

After successful logon AD FS server (sts.mydomain.com) redirects the browser to the UAG instance, in this case: https://portal.mydomain.com/InternalSite/ADFSv2Sites/federation/Default.aspx)

Post-validation occurs before the user is then authenticated against Sharepoint

And we’re in.. let’s have a quick look at the user settings:

The i:0#.w|MYDOMAIN\280368 account value is our Kerberized logon. As can be seem from the screenshots, I set out doing this test with Sharepoint 2010, configuring a Sharepoint 2010 teamsites web application to use Integrated Windows Authentication (IWA).

As can be seen from the above screenshot, I’ve configured the SharePoint web application in UAG to use Kerberos Constrained Delegation for single sign-on (with an SPN of http/*). This doesn’t mean that I’m no longer using AD FS, rather I’m doing AD FS logon at the trunk and then delegating logon: translating the Name claim extrapolated from AD FS and pass the value onto Active Directory as the shadow account user. Microsoft call this Federated trunk with non-federated web applications.

Aside from the above screenshot, I amended the web application on my portal trunk from the previous blog. For validation, here are the settings on each tab of the web application:

General : Default
Web Servers tab

points to internal FQDN / Load Balanced VIP of the Sharepoint web farm
public name is set to teams.mydomain.com

Authentication (as per graphic)

Use SSO checkbox is ticked
Use Kerberos Constrained Delegation for Single Sign-on radio dialog is selected
Application SPN is set to http/*
KCD Value Name is set to Name

Download/Upload : Default
Portal Link

Add Portal and toolbar link is unchecked

NB: I’ve set teamsites to be my initial internal application also for the trunk (see below)

Authorization : Default (at the moment)
Web Security : Default
Cookie Encryption : Default
Endpoint Policy Settings : Default

One additional change that I did do, as the Portal link section alluded to, I’ve set the Teamsites application as my home application on the main trunk configuration page.

AD FS 2.0 Settings

Within AD FS, there should be a relying party setup pointing to the external interface of the UAG (as described in the previous blog post).

https://portal.mydomain.com/InternalSite/ADFSv2Sites/Federation/FederationMetadata/2007-06/FederationMetadata.xml

In addition, the following claims rules are setup on the Relying Party (Name is the key):

Pass thru Name
Pass thru Role
Pass thru UPN
Pass thru E-Mail Address

IIS Settings

For reference purposes I’ve included IIS settings. I’m not suggesting that you set your Sharepoint web application settings via IIS manually; rather, it can be useful to see the end-product/result in IIS Smile

SSL Host header is set to https://teams.mydomain.com
Wildcard certificate is set on the Sharepoint website
SPN set to the FQDN of the Sharepoint web application pool (service account)

Authentication Advanced Settings

Extended Protection = Accept
Kernel Mode Authentication = True

Sharepoint 2010

I did setup an SPN for teams.mydomain.com using the corresponding Sharepoint service account for the MOSS web application, e.g.

Setspn –S http/teams.mydomain.com MYDOMAIN\sa_apppool1

Under Authentication Providers in Sharepoint, I turned off the AD FS Trusted Identity Provider I’d configured in the previous blog entry and now re-enabled Windows Authentication, setting Integrated Windows Authentication and Negotiate (Kerberos).

I’d mostly definitely recommend testing the Sharepoint web application internally before playing around with UAG. Use IEHTTPHeaders or HTTPWatch or a similar plug-in to ensure that Kerberos is working and that the browser is not downgrading authentication to NTLM. This is key to avoid any sort of spurious errors within UAG … errors along the lines of “you do not have permission to access this folder” spring to mind

Within Sharepoint, for test purposes, I also added the Domain Users built-in group to the site visitors group

Not the most secure configuration, but good for testing Smile

So what are the benefits of this approach?

Front-end authentication protocols may differ from back-end authentication protocols. For ISA/TMG/IAG/UAG admins, this is a familiar concept, but it can now be applied to federation protocols at the front-end.
It provides a means of projecting claims-based identities to “legacy” web applications that are not claims-aware or are not ready to step over to claims. This allows us to extend the federation concept to legacy applications.

Regards,

Mylo

AD FS 2.0–Inside and Outside

November 4, 2010AD FS 2.0, Claims-based Authentication, DirectAccess, Forefront UAG, Sharepoint 2010AD FS 2.0, DirectAccess, Forefront UAG, Sharepoint 2010mylo

If you’ve had the good fortune of setting up AD FS 2.0 in the last few months, then no doubt you’re seeing the various capabilities and nuances of such a solution. As a new product though, while “free”, working with such technology can be frustrating. Not having the pleasure of seeing someone else going through that pain barrier that you are, nor being able to learn from someone else’s mistakes rather than yours, can make for difficult times … Nonetheless, I’ve been running various sandpits and configurations now since Q4 2009 (with admittedly varying degress of success) and I really had been meaning to make note of some of this earlier.. it was the recent release of UAG 2010 SP1 RC that provided the necessary motivation.

In this post I’m describing Web SSO scenarios, using a single corporate Active Directory for internal and external access. I look at a few possible approaches:

AD FS Proxy Forms-Based Authentication for Internet users
Intranet AD FS Logon using Integrated Windows Authentication (IWA)
UAG-based logon thru “portal” logon and RP-initiated Logon for Internet users using UAG SP1 RC.

I’m using split-DNS in my test sandpit.. mydomain.com registered (A) records point to the AD FS proxy and the TMG in Scenario 1 for AD FS and Sharepoint respectively. In Scenario 3, the UAG portal trunk is the destination for both AD FS and Sharepoint. Scenario 2 has the A record for the AD FS STS pointing to the internal AD FS farm and the internal Sharepoint web farm(s).

Scenario 1 – Internet Access

Prerequisites

Internet connectivity (although testing via VMs is perfectly acceptable)
Browser (IE / Mozilla)
Forefront TMG 2010 SP1
AD FS 2.0 Server
AD FS 2.0 Proxy
Relying Party (I elected to use Sharepoint 2010 in this example, although a CRM 2011 IFD also works fine… )

sts.mydomain.com – pointing to the Internet registered (A) record for the AD FS Proxy

teams.mydomain.com –pointing to a RP (e.g. Sharepoint 2010)…

I used TMG in the sandpit to protect my relying party (Sharepoint)…. It’s worth noting that TMG is acting as a simple Reverse Proxy here. There’s no pre-authentication on the web listeners, no FBA, no Windows Auth. The user is logging on via the AD FS proxy, before they can gain access to the Relying Party (via TMG). If that’s not clear enough… let me put it another way .. TMG is not involved in the logon process at all … i.e. AD FS based logon thru TMG is not a supported configuration (not to mention I can’t get it working either). There are, however, still potential advantages to be had, in using the TMG as the reverse proxy; namely in protecting the relying party (Network Inspection System and Enhance Malware Protection spring to mind).

As a footnote, I ended up using a wildcard certificate for testing in this scenario ; a single web listener on TMG will suffice with multiple web publishing rules per relying party (in this case per web application in Sharepoint 2010). Note that it is possible to put the AD FS proxy itself behind TMG and this works (although this adds another SSL hop to the access equation) and again, there’s no authentication configured on the listener.

Scenario 2 – Intranet/Internal Users: Integrated Authentication : IWA and AD FS

Prerequisites

Local Intranet/Corporate Connection
A Browser (IE / Mozilla)
AD FS 2.0 Server
Active Directory
Relying Party

In an Intranet scenario, we can leverage the SSO capability that AD and WIF can offer through integrated authentication. The client is using local DNS and is pointing directly to the AD FS farm rather than the proxy. In this example, I’ve added the STS needs to the local Intranet zone. If you’re using Mozilla in your tests here, you’ll need to go into about:config in the browser and add the STS to both the network.negotiate-auth.delegation-uris and network.negotiatea-auth.trusted.uris for Kerberos to work.

Scenario 3 : Internet Access (with UAG)

Prerequisites

– All the above plus UAG 2010 SP1 RC

When I saw that UAG SP1 (RC) now supports AD FS 2.0, I danced a little jig (albeit in my mind… I am at best, sadly, a poor dancer… my right leg is a PC, my left is a Mac…..that’s how well they get on)…. Anyway, with UAG 2010 supporting AD FS 2.0, this little offering enhances the use case at the edge.

As the name suggests with UAG, this is unified access… so all access in this scenario is thru said gateway. In this capacity, UAG (portal.mydomain.com) is a Relying Party. As the SP1 RC documentation, recommends, I created a trunk and configured AD FS as an authentication provider in UAG.

There are two access scenarios with UAG here. The first is accessing the portal trunk itself with the application available on the UAG portal, the second is calling the application directly (RP-initiated logon)

Portal-based Logon

Logging in thru portal.mydomain.com, I’m entering the UAG URL directly rather than the application (teams.mydomain.com).

First time I logon, I elect to trust the site for this session… (all the UAG ActiveX controls were installed earlier)…. because my AD FS test rig is configured with two test claims providers, Employees and Partners, we need to go thru Home Realm Discovery.. I’m logging into Employees.. (Partners is another IdP)

Now we’re in the UAG portal screen

I select the “Teamsites” application and off we go and we’re in Sharepoint

RP-Initiated Logon

This process incorporates less steps and is a more likely usage scenario particularly with users bookmarking the relying party in the browser.. duly noted… here I access a Teamsites favourite that I’ve created in my browser of choice; taking me to https://teamsites.mydomain.com.

Again, I go thru Home Realm Discovery (HRD) and select Employees

Forms-based Logon at the AD FS Proxy using my trusty user ID.

This time there’s no Portal rendition, and it’s straight into the application.

UAG Configuration Notes

Here’s some barebones configuration notes.. this is not a step-by-step, rather a summary of the salient points (as I recall them)…

Create a new portal trunk and under this trunk (e.g. portal.mydomain.com) create our authentication server using the new AD FS 2.0 Server Type.

Retrieve the federation metadata and select a leading claim value (I’ve used Name). This will automatically create a new AD FS 2.0 application and Application Type .. make a note of the UAG Relying Party endpoint.. this is required when configuring the Relying Party in AD FS….. syntax is along the lines of..

https://portal.mydomain.com/InternalSite/ADFSv2Sites/Federation/FederationMetadata/2007-06/FederationMetadata.xml

You can test availability of the metadata via the browser.. note that this must resolve to the external trunk address rather than any internal address of the UAG server (this is mentioned in the documentation).

After it’s created we can pop in and look at the application properties… I didn’t have to change any settings within.

At this point it was time to create an application in UAG for our test Teamsites application… as can be seen from the subsequent shot.. we elected to use the AD FS authentication server here..

Incidentally, I elected to check the Portal and toolbar link checkbox as I wanted to test accessing the Sharepoint application thru the portal itself (as described earlier).

A couple of final notes…

Make sure the UAG portal URL, the AD FS STS and the RP are in the same browser zone otherwise spurious errors such as the one below will appear. Again, the help file does mention this, but ….

I used Local Intranet Zone as I have an Intranet access scenario (2) which uses Kerberos-based logon..

I’ve also tried this configuration from the Internet using a Windows 7 domain joined client using DirectAccess and everything works smoothly with integrated auth … great stuff..

The UAG RC documentation states that you can configure AD FS to use forms-based authentication, however, UAG does not support this configuration by default. Now I initially read this as meaning that the FBA is not supported, however, that didn’t make much sense to me so I assumed that I’d misinterpreted the meaning of the RC documentation and chose to ignore it Smile …

Next test stop is either going to be KCD testing with Shadow accounts (which looks pretty interesting ) or adding the CRM 2011 Beta IFD to UAG…

Hope this helps somebody/somewhere..

Mylo

The Access Onion

Access Management and Identity Federation on a plate.

Category Archives: Claims-based Authentication

MFA Conditional Access Policies in AD FS 2012 R2

MFA with Client Certificates in ADFS 2012 R2

Exchange 2013 SP1, Outlook Web App (OWA) and AD FS

First Impressions – AD FS and Window Server 2012 R2 – Part II

First Impressions – AD FS and Windows Server 2012 R2 – Part I

Architecture Changes

Workplace Join / Bring Your Own Device (BYOD)

Web Application Proxy

Extranet Soft Account Lockout

Lost Device Protection

Step-up Authentication Scenarios with AD FS 2.0 Part II

Virtual Smart Cards (VSC) and AD FS 2.0

Step-Up Authentication Scenarios with AD FS 2.0 Part I

UAG 2010 and AD FS 2.0 updated articles

Claims-based access with AD FS 2.0 and PointSharp Identity Federation

Exchange 2010 OWA, Claims-based Authentication and AD FS

AD FS 2.0 Rollup 2 and WHR – We Has Resolution (Part 2)

Federated SSO Logon with AD FS 2.0 in an Extranet with UAG

O365 and TMG with Strong Authentication (Part II)

Using TMG as a strong-authentication capable proxy for passive O365 clients and reverse proxy for rich/active clients

O365 and TMG with Strong Authentication (Part I)

This post looks at how TMG 2010 may occupy a role of hybrid AD FS Proxy for Office 365.

Adding multiple claims-aware web applications to a Sharepoint 2010 Farm.

The Triumvirate: UAG 2010SP1, AD FS 2.0 and Kerberos

AD FS 2.0–Inside and Outside