Tag: AD FS 2016

AD FS 2016 Access Control Policies troubleshooting

The Access Control (AC) policies were introduced in AD FS 2016.

See this official documentation to get familiar with AD FS Access Control policies concept and settings.

Recently had to troubleshoot the following scenario.

Customer has Hybrid Exchange environment with email boxes located in on premises Exchange 2010 and archives located in Exchange Online.

Exchange on premises did not have Modern Authentication enabled.

Office 365 domain federated with AD FS 2016.

AD FS was configured to use Azure MFA.

The goal was to require MFA for all external users using Outlook 2016 and accessing their mailboxes and archives and skip MFA if the user is located inside corporate network.

At the beginning the following AD FS AC policy was configured for Office 365 Relying Party Trust (RPT).

{
Permit users
	and when authentication includes MFA
except
	from 'intranet' location;

Permit everyone
}

The issue with this policy is the “Permit everyone” at the second part, since this rule will allow anybody who didn’t meet requirement in first policy, to authenticate.

So the AD FS AC policy was modified the following way and applied to O365 RPT.

{
Permit users
	and when authentication includes MFA
except
	from 'intranet' location
}

And that’s where the unexpected authentication pop-up windows and MFA prompts started to happen when users inside corporate network were opening Outlook to access their email.

User continuously was receiving the Windows Security pop-up window that didn’t except correct user credentials and there was a second pop-up asking to authenticate again and that was triggering the MFA call to the user’s phone.

Analyzing the authentication flow based on the Exchange layout mentioned above, it was confirmed that its expected to have following authentication events to happen:

  1. User accessing email box located in on premises Exchange must authenticate via AD FS using legacy authentication from Intranet.
  2. When accessing email archive, Exchange Online has to authenticate user as well and since the legacy authentication was used, Exchange Online was authenticating on behalf of the user from outside of the corporate network.

By the way, due to the fact of legacy authentication flow we were not able to use Microsoft Claims X-Ray service.

To reduce the impact to production users, it was recommended to change the Access Control policy to contain these settings:
1. Permit users from the security group with MFA and exclude Intranet
2. Permit users from the security group with MFA and exclude Internet if the client IP (public IP of the office) matches the regex.
3. Permit all.

AD FS Access Control policy now looked like this.

{
Permit users
	from 'TEST' group
	and when authentication includes MFA
except
	from 'intranet' location;

Permit users
	from 'TEST' group
	and when authentication includes MFA
except
	from 'extranet' location
	and with 'http://schemas.microsoft.com/2012/01/requestcontext/claims/x-ms-client-ip' claim regex matches 'regex_for_public_IP_of_the_office' in the request;

Permit everyone
}

Applied this AD FS AC policy to Office 365 RPT and still there were two prompts when the Outlook 2016 is opened – basic authentication window when accessing on premises email box and Modern Authentication prompt with MFA when accessing EXO archive.

In the AD FS Admin logs we saw the error: “MSIS5007: The caller authorization failed for caller identity XXX for relying party trust urn:federation:MicrosoftOnline.”

And in the AD FS Debug logs see the MFA is still required regardless the fact that the authentication attempt is coming from Intranet.

After multiple additional tests and getting better understanding how the Access Control policies are applied the following AD FS AC Policy was crafted that has addressed the issue completely.

{
Permit users 
	from 'extranet' location
	and from ‘TEST’' group
	and with 'http://schemas.microsoft.com/2012/01/requestcontext/claims/x-ms-forwarded-client-ip' claim regex matches 'regex_for_public_IP_of_the_office' in the request;

Permit users 
	from 'extranet' location
	and from 'TEST' group
	and when authentication includes MFA
except 
	with 'http://schemas.microsoft.com/2012/01/requestcontext/claims/x-ms-forwarded-client-ip' claim regex matches 'regex_for_public_IP_of_the_office' in the request;

Permit users 
	from 'intranet' location
	and from 'TEST' group;

Permit everyone
} 

The AD FS Access Control polices above work the following way:
1. Permits authentication coming from Internet if its EXO legacy authentication protocol on behalf of the user in the test security group coming from office public IP address;
2. Permits any other authentication for the test group coming from Internet if the MFA completed, but excludes office public IP from this rule (to make sure the first rule works as expected);
3. Permits authentication from the Intranet with no MFA for the test group (authentication to on premises Exchange)
4. And the last one catch Permit All group to make sure prod users are not affected during testing.

ADFS Access Control Policy

When the AD FS AC policy was successfully tested with the users added to the TEST group, the policy was applied to the rest of the production users by removing the TEST group condition from the first three policies and removing “Permit everyone”.

AD FS 2016 Extranet Smart Lockout eventIDs 1203 and 1210 clarification

Continuing my journey of learning the great AD FS Extranet Smart Lockout (ESL) feature.

As mentioned in my other post, the enhancement were made in AD FS 2016 auditing and there will be Event ID 1203 logged in the ADFS Security log by ADFS Auditing in case there was a failure to validate user credentials against Active Directory.

When you have enabled ADFS Extranet Smart Lockout feature in either log or enforce mode and AD FS Security auditing was enabled (the user has AD FS ESL bad password counts set to zero), as soon as the external bad password attempt count reaches the value specified in the ExtranetLockoutThreshold (you will see event ID 1203 for each bad password attempt), the account will be locked out on AD FS for a duration specified in the ExtranetObservationWindow, the event ID 1210 will be logged in Security event log and password validation attempts will not be sent to Active directory.

As mentioned in AD FS ESL public documentation:

AD FS will write extranet lockout events to the security audit log:

  • When a user is locked out (reaches the lockout threshold for unsuccessful login attempts)
  • When AD FS receives a login attempt for a user who is already in lockout state

At the same time, no event ID 1203 will be logged, since no password validation against Active Directory is taking place.

Only after the extranet observation window expires, the password attempts will be forwarded to AD and if the password validation fails, the event ID 1203 is logged.

Please note, that the CurrentBadPasswordCount value in event ID 1210 only increases when the password validation happens against AD and at the time the account is locked on AD FS.

Also keep in mind, that when the AD FS ESL extranet observation window expires, it doesn’t clear the AD FS ESL bad password count until good password was provided, so one single 1203 event from the same bad IP location with no bad password counts cleared will put account in ESL state again for the time specified in the ExtranetObservationWindow.

Hope this information will be helpful for you.

AD FS Extranet Smart Lockout user management via remote PowerShell

Recently had experienced issue when trying to execute AD FS Extranet Smart Lockout user management cmdlet via remote PowerShell.

Invoke-Command -ComputerName Win2016-ADFS01 -scriptBlock {Get-AdfsAccountActivity -Identity user@domain.com}

Error in PowerShell:

Exception of type
‘Microsoft.IdentityServer.User.UserActivityRestServiceException’ was thrown.
+ CategoryInfo         : NotSpecified: (:) [Get-AdfsAccountActivity], User
ActivityRestServiceException
+ FullyQualifiedErrorId : Microsoft.IdentityServer.User.UserActivityRestSer
viceException,Microsoft.IdentityServer.Management.Commands.GetAdfsAccountAc
tivity
+ PSComputerName       : Win2016-ADFS01

In AD FS Admin logs on Win2016-ADFS01 server saw following error:

Log Name:     AD FS/Admin
Source:       AD FS
Date:         10/29/2018 5:20:39 PM
Event ID:     1100
Task Category: None
Level:         Error
Keywords:     AD FS
User:         domain\adfs_service_account
Computer:     Win2016-ADFS01
Description:
The Federation Service could not authorize a request to one of the REST endpoints.
Additional Data
Exception details:
Microsoft.IdentityServer.WebHost.Rest.RestRequestAuthorizationFailedException: Only AD FS Service can access this endpoint. The client was authenticated as NT AUTHORITY\ANONYMOUS LOGON.
at Microsoft.IdentityServer.Web.UserActivity.UserStoreAuthenticationVerificationMethod.VerifyTrustedRequest(WrappedHttpListenerContext context, String& auditInformation)
at Microsoft.IdentityServer.Web.Rest.RestRequestHandler.OnGetContext(WrappedHttpListenerContext context)

Solution was to enable CredSSP on management machine and Win2016-ADFS01 server and use following commands:

$cred = Get-Credential
Invoke-Command -ComputerName Win2016-ADFS01 -Authentication Credssp -credential $cred -ScriptBlock {Get-AdfsAccountActivity user@domain.com}

You can read more about managing the second hop in PowerShell remoting and consideration when enabling CredSSP in this article – https://docs.microsoft.com/en-us/powershell/scripting/setup/ps-remoting-second-hop?view=powershell-6

Update 2-14-2019: Microsoft has updated the documentation how to delegate ADFS PowerShell access to non-admin users – https://docs.microsoft.com/en-us/windows-server/identity/ad-fs/operations/delegate-ad-fs-pshell-access

 

AD FS 2016 Extranet Smart Lockout behavior

I’m sure you are familiar with the following articles discussing the Federated account lockouts and AD FS Extranet Smart Lockout (ESL) feature and set up recommendations.

https://blogs.technet.microsoft.com/tspring/2017/01/20/federated-to-microsoft-cloud-and-account-lockouts/

https://docs.microsoft.com/en-us/windows-server/identity/ad-fs/operations/configure-ad-fs-extranet-smart-lockout-protection

https://samilamppu.com/2018/07/09/w2016-adfs-smart-lockout/

Recently was helping the customer whose environment was experiencing high volume of on-premises AD accounts lockouts due to the external bad passwords attempts via AD FS 2016 farm.

As per second article, Microsoft recommends enabling the AD FS ESL in the log only mode. It is recommended to run AD FS ESL in such mode for 5-7 days to build the list of familiar locations per user.

Since the impact of the AD lockouts was high to the customer, they decided to switch from log to enforce mode after 24 hours of enabling the ESL, but ran into following issue.

It was not enough time to build the familiar IPs list, and some users accounts still experiencing heavy bad passwords attempts were locked out on AD FS side due to empty familiar IP addresses list.

This happened because in case in the output of Get-AdfsAccountActivity PowerShell cmdlet you see the familiar IP list is empty and the UnknownLockout = True, the user will not be able to sign in with correct password until the observationWindows time elapses or ADFS admin resets the count. In such scenario AD FS ESL works in AD FS Extranet Lockout mode introduced in AD FS 3.0.

This issue was addressed in AD FS 2019 where you can enable audit mode for smart lockout while continuing to enforce the soft lockout behavior (ADPasswordCounter)