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
	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
	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
	from 'intranet' location;

Permit users
	from 'TEST' group
	and when authentication includes MFA
	from 'extranet' location
	and with '' 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 '' 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
	with '' 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”.


PowerShell script to collect ADFS Extranet Smart Lockout events sequence

Below is slightly modified script from here to collect the sequence of the EventIDs 1203 and 1210 on single AD FS server that might help you understanding and troubleshooting the AD FS Extranet Smart Lockout (ESL) behavior.

You can read more about AD FS ESL behavior here and here.

$events = Get-WinEvent -MaxEvents 2000 -FilterHashtable @{Logname='Security';Id=1203,1210}
$events2 = ($events | select ID, Message,TimeCreated -ExpandProperty Message)
$info = @()

$events2 | foreach {

$IpAddresses = $null
$UserId = $null
$BadCount = $null

    $IpStart = $_.Message.IndexOf("<IpAddress>")
    $IpEnd = $_.Message.IndexOf("</IpAddress>")
    $IpAddresses = $_.Message.Substring($IpStart+11,($IpEnd-$IpStart-11))

    $UserIdStart = $_.Message.IndexOf("<UserId>")
    $UserIdEnd = $_.Message.IndexOf("</UserId>")
    $UserId = $_.Message.Substring($UserIdStart+8,($UserIdEnd-$UserIdStart-8))
 if ($_.Id -like 1210) 
    $BadCountStart = $_.Message.IndexOf("<CurrentBadPasswordCount>")
    $BadCountEnd = $_.Message.IndexOf("</CurrentBadPasswordCount>")
    $BadCount = $_.Message.Substring($BadCountStart+25,($BadCountEnd-$BadCountStart-25))
    else {$BadCount = $null}

$Fail = New-object -TypeName PSObject
add-member -inputobject $Fail -membertype noteproperty -name "EventID" -value $_.Id
add-member -inputobject $Fail -membertype noteproperty -name "TimeStamp" -value $_.TimeCreated
add-member -inputobject $Fail -membertype noteproperty -name "IPaddress" -value $IpAddresses
add-member -inputobject $Fail -membertype noteproperty -name "User ID" -value $UserId
add-member -inputobject $Fail -membertype noteproperty -name "BadCount" -value $BadCount

$info +=$Fail
$info | ft

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 vis 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}

Error in PowerShell:

Exception of type
‘Microsoft.IdentityServer.User.UserActivityRestServiceException’ was thrown.
+ CategoryInfo         : NotSpecified: (:) [Get-AdfsAccountActivity], User
+ FullyQualifiedErrorId : Microsoft.IdentityServer.User.UserActivityRestSer
+ 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
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}

You can read more about managing the second hop in PowerShell remoting and consideration when enabling CredSSP in this article –

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.

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)

Internal application published via Azure AD Application Proxy access issues troubleshooting

Recently was troubleshooting the issue when the internal application portal page was not loaded (part of the portal was not loaded at all) when accessed via Azure AD Application Proxy (AAD AP). The application in question was Dell Storage Manager web console, but the troubleshooting steps described below are applicable to any application.

First thing checked the Azure AD application settings related to AAD AP – Azure AD pre authentication was used, no custom domain, headers and application body translation enabled, so setup looked pretty standard.

As next step captured the Fiddler trace when accessing the internal application directly and via AAD AP.

In the trace for the AAD AP access see one of the pages fail to load and this error message:

Azure AD Application Proxy
Root cause: The connector did not respond within the timeout period.
Status code:  GatewayTimeout
Url:  https://xxx/messages
TransactionID:  XXX
ConnectorGroupId:  XXX
Timestamp:  9/4/2018 6:50:00 PM

At the same time, the “messages” page is successfully loaded when the application is accessed directly from the corporate network.

Looking closer at the request and response in both Fiddler traces see next.

Request (redacted):

GET https://IntenalHostName/messages HTTP/1.1
Origin: https://IntenalHostName
Sec-WebSocket-Key: =
Connection: Upgrade
Upgrade: Websocket
Sec-WebSocket-Version: 13
User-Agent: Mozilla/4.0
Host: IntenalHostName

Response (redacted):

HTTP/1.1 101 Switching Protocols
Expires: 0
Cache-Control: no-cache, no-store, must-revalidate
X-Powered-By: Undertow/1
Server: WildFly/8
Pragma: no-cache
Origin: https://IntenalHostName
Upgrade: WebSocket
Sec-WebSocket-Accept: pDsDNKGWwSG8=
Date: Tue, 04 Sep 2018 GMT
Connection: Upgrade
Sec-WebSocket-Location: wss://IntenalHostName/messages
Content-Length: 0

In the bad Fiddler see following:

Request (redacted):

Sec-WebSocket-Key: nl/CD3hakpNw==
Connection: Upgrade
Upgrade: Websocket
Sec-WebSocket-Version: 13
User-Agent: Mozilla/5.0
DNT: 1
Cache-Control: no-cache
Cookie: dsmUsername=; JSESSIONID=ZEfQJAHRszfZGXql33h06aRw.vdellem01; AzureAppProxyUserSessionCookie


HTTP/1.1 504 Gateway Timeout

So the issue seems to be happening when there is a request to upgrade to Websocket.

The Websocket support by Azure AD App Proxy is currently in preview and it was recommended to collect additional logs to see if it can be fixed in the current case.

To enable the verbose Connector logs, it was recommended to make these changes:

  1. Locate the installation directory of the connector (should be C:\Program Files\Microsoft AAD App Proxy Connector)
  2. Open the file ApplicationProxyConnectorService.exe.config in notepad for edit
  3. Add the following section right after appSettings:

  <trace autoflush=”true” indentsize=”4″>
      <add name=”consoleListener” type=”System.Diagnostics.ConsoleTraceListener” />
      <add name=”textWriterListener” type=”System.Diagnostics.TextWriterTraceListener” initializeData=”<PATH_WITH_WRITE_PERMISSIONS> \ConnectorTrace.log” />
      <remove name=”Default” />

  • Make sure to change to a path with write permissions
  1. Restart the connector service and reproduce the issue from your PC while capturing the Fiddler trace.

Looking at the logs, found this exception entry:

System.Net.WebSockets.WebSocketException (0x80004005): Unable to connect to the remote server —> System.Net.WebException: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel. —> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure.

As the next step, tried to access the application directly from the Connector server using the Internet Explorer browser and sure thing the browser complained about SSL error.

Looking closer, noticed that the internal application URL was protected by SSL certificate issued to the host running the application.

As soon as the application URL was changed to server host name on the AAD App Proxy side, the issue was resolved.

AD FS Relying Party certificates errors troubleshooting (EventID 317)

Customer has configured the new Relying Party Trust by using the Relying Party Trust Wizard and importing the data from the file that was downloaded earlier on the management computer.

When testing the Relying Party sign-on, the application was returning the error

“An error SAML response status was received. urn:oasis:names:tc:SAML:2.0:status:Responder”

Per following article this means “The request could not be performed due to an error on the part of the SAML responder or SAML authority.”

Looking at the AD FS event logs, located the following self-explanatory error corresponding to unsuccessful sign in attempt.

Log Name:      AD FS/Admin
Source:        AD FS
Date:          7/3/2018 9:55:33 AM
Event ID:      317
Task Category: None
Level:         Error
Keywords:      AD FS
User:          xxx
Computer:      XXX
An error occurred during an attempt to build the certificate chain for the relying party trust ‘microsoft:identityserver:XXX’ certificate identified by thumbprint ‘xxx’. Possible causes are that the certificate has been revoked, the certificate chain could not be verified as specified by the relying party trust’s encryption certificate revocation settings or certificate is not within its validity period.
You can use Windows PowerShell commands for AD FS to configure the revocation settings for the relying party encryption certificate.
Relying party trust’s encryption certificate revocation settings: CheckChainExcludeRoot
The following errors occurred while building the certificate chain: 
A certificate chain could not be built to a trusted root authority.
The revocation function was unable to check revocation for the certificate.
The revocation function was unable to check revocation because the revocation server was offline.
User Action:
Ensure that the relying party trust’s encryption certificate is valid and has not been revoked.
Ensure that AD FS can access the certificate revocation list if the revocation setting does not specify “none” or a “cache only” setting.
Verify your proxy server setting. For more information about how to verify your proxy server setting, see the AD FS Troubleshooting Guide (

Per environment’s security requirements, the AD FS server had no Internet access, that is why the Certificate Revocation List checks for the Relying Party Encryption and Signing certificates were failing.

Please note, that this is not recommended to turn of the revocation checking, that is why you might review your firewall policy for external connections to the Internet for AD FS and WAP (

While the security team was reviewing the option allowing outbound connections from ADFS to some public Certificate Authority CRL URLs, we have used following switches in the Set-ADFSRelyingPartyTrust PowerShell command, to disable Relying Party certificates CRL check by setting the values to None.

-EncryptionCertificateRevocationCheck and – SigninCertificateRevocationCheck

Per this article these are the acceptable values:

–          None (this is default value)

–          CheckEndCert

–          CheckEndCertCacheOnly

–          CheckChain

–          CheckChainCacheOnly

–          CheckChainExcludingRoot

–          CheckChainExcludingRootCacheOnly

AD FS 2.0 and Safari (iOS 9 and iOS 10) sign in issue (authentication cookies size issue)

Recently have been working on the issue when the users on iOS 9 and 10 were not able to complete the authentication from outside of corporate network (via AD FS Proxy). The users were getting the error – “There was a problem accessing the site. Try to browse to the site again. Reference number: XXX”.

The same users from iOS 11 had no issues signing in via the same AD FS farm.

The users were the members of 150-200 on premises AD security groups.

It took me some time to go over basic troubleshooting and making sure the AD FS servers have all needed patches installed –, but the issue persisted.

Turned out to be a known issue, when the older Safari versions have cookies size limitation.

Looking at the captured Fiddler trace we saw the AD FS was issuing 5 MSISAuth cookies (total size around 9 Kb) and when Safari was redirected to ADFS to get the access token, only 4 MSISAuth cookies were posted to ADFS (around 8 Kb). In this case Safari was dropping the cookies.

In order to work around this issue, the customer decided to do not pass all 200 security groups in the claims.

In order to achieve this, the default “Pass through all Group SID claims” was replaced with following claim rule since the customer was using these groups in his Authorization claim rules:

c:[Type == ““, Value =~ “S-1-5-21-XXXXXXXX-XXXXXXXXXX-XXXXXXXXX-XXX840|S-1-5-21-XXXXXXXXX-XXXXXXXXX-XXXXXXXXXX-124XXXX”, Issuer == “AD AUTHORITY”] => issue(claim = c);

Azure Multi-Factor Authentication Server not sending emails out for new users

Recently was troubleshooting the issue when no email is sent to the new MFA server users regardless all the configurations seems to be correct. See following official documentation for more details. 

Because Administrator was able to send the Update email to the end user, we excluded the improper SMTP server configuration.

Per MFA server Help file: New Users – An email is sent to a user added that is enabled and complete (phone specified, mobile app activated, or OATH token secret key specified), or to an updated user that was either disabled or incomplete and is now enabled and complete.

Note: Emails are only sent when Send email to users is checked and the user’s email address is specified or their username is in email address format.

Confirmed that the New user has “Send email” check box selected on the User profile General Tab and the email address is correct.


Also, by going to MFA UI – Email – Email Context confirmed all the New User templates have correct email address specified in the From field.

Checked the SMTP server logs and don’t see any email send attempt from MFA server for New User email, only connections for Update email to be send.

Time to check the MFA Server logs!

To make sure you are looking at the latest logs, go to MFA UI – Logging – View Log Files.

Looking at the MultiFactorAuthAdSyncSvc.log see following error correlating to the time when the new user was added:

2018-03-07T18:20:20.006280Z|e|2960|4036|pfadssvc|***** ERROR ***** Error sending email to Access to the path ‘\\FileShare\public\MFA-Instructions\MFA-Guide.pdf’ is denied.

So the Administrator used the Attachment option to send additional instructions to new users, but the File share had access restrictions preventing the MFA server Local System account reading this document.


Solution was to either move the MFA instructions files to the MFA server or adjust the file share access permissions to allow Everyone to read the files.

Morale of the story: Read the manuals and logs, those are written by smart people 😊

Azure AD device registration error codes

Even when you followed the Hybrid Azure AD join instructions to set up your environment ( ), you still might experience some issues with the computers not registering with Azure AD.

To check if the device was joined to Azure AD run “dsregcmd /status” command in command prompt and look at AzureAdJoined value. For the Azure AD registered devices, it should be set to YES.

If the AzureAdJoined says NO, next step will be to collect information from the Application and Services – Microsoft – Windows – User Device Registration – Admin logs.

First thing, try to locate and read the text description in the error to see if it gives any clue.

Below are some examples of the errors and possible solutions to try.

User Device Registration Admin log – EventID 304 or 305adalResponseCode: 0xcaa1000e – recommended step is to check the AD FS claim rules per mentioned above article. It is important to have the AD FS claim rules in the described order and if you have multiple verified domains, do not forget remove any existing IssuerID rule that might have been created by Azure AD Connect or other means.

User Device Registration Admin log –wmain: Unable to retrieve access token 0x80004005 – recommended step is to check the AD FS claim rules.

User Device Registration Admin log – EventID 305AdalErrorCode: 0xcaa90006 – make sure the computer is able to reach and authenticate to specified in the error text description Identity Provider endpoint.

User Device Registration Admin log – EventID 204 – Error code: 0x801c03f2 (“The device object by the given id (xxx) is not found.”) – make sure the on-premises computer object is synchronized to Azure AD. Run the Full Azure AD Connect sync.

User Device Registration Admin log – EventID 304 (309, 201 and 233 coming before it) – Error code: 0x801c0021 (Error code: 0x80072efe in EventID 201) – most likely the network or proxy didn’t allow the connection to Azure AD device registration endpoints or IdP to complete authentication. 

Sometimes the error description of the User Device Registration Admin log event is not providing enough information and you have to enable the User Device Registration Debug log to get more information.

To enable debug logs open Event Viewer – check “Show Analytic and Debug Logs” and browse to Application and Services – Microsoft – Windows – User Device Registration – right click on Debug log and select Enable log.

To trigger the device join attempt you have to open Command prompt as System account (you can use Sysinternals PsExec – psexec -i -s cmd.exe) and issue “dsregcmd /debug /join” command. After that disable the Debug log, check the Admin logs and if still the error description is not informative go to Debug logs.

Example 1:

Log Name:      Microsoft-Windows-User Device Registration/Admin
Source:        Microsoft-Windows-User Device Registration
Date:          2/9/2018 10:17:49 AM
Event ID:      304
Task Category: None
Level:         Error
User:          SYSTEM
Computer:      XXX
Automatic registration failed at join phase.  Exit code: An unexpected internal error has occurred in the Platform Crypto Provider.

User Device Registration Debug log –

Log Name:      Microsoft-Windows-User Device Registration/Debug
Source:        Microsoft-Windows-User Device Registration
Date:          2/9/2018 10:23:30 AM
Event ID:      500
Task Category: None
Level:         Information
User:          SYSTEM
Computer:      XXX
wmain: failed with error code 0x80290407.

Most likely this error is an indication that the TPM is not supporting Azure AD join requirements ( ).

Next steps for this particular issue I would recommend for these stations are:

  • Ensure the TPM is in 2.0 mode. You will find this setting in the BIOS.
  • As a last resort, disable TPM in the BIOS, so Azure AD Join process uses software-based keys.

Example 2:

Log Name:      Microsoft-Windows-User Device Registration/Admin
Source:        Microsoft-Windows-User Device Registration
Date:          4/17/2018 12:44:10 PM
Event ID:      304
Task Category: None
Level:         Error
User:          SYSTEM
Computer:      XXX
Automatic registration failed at join phase.  Exit code: Keyset does not exist. Server error: empty.

After running dsregcmd /debug /join see following in the output:

DsrDeviceAutoJoinFederated failed with -2146893802
wmain: failed with error code 0x80090016.

Most likely this error indicates that the machine was imaged from the already Azure AD registered computer. Also it might indicate the TPM issues (see the TMP troubleshooting steps mentioned above).

If the fist is true, try renaming the “C:\ProgramData\Microsoft\Crypto\Keys” folder and re-running the dsregcmd /debug /join.

Example 3:

Log Name:      Microsoft-Windows-User Device Registration/Admin
Source:        Microsoft-Windows-User Device Registration
Date:          5/16/2018 8:44:03 AM
Event ID:      305
Task Category: None
Level:         Error
User:          SYSTEM
Computer:     XXX
Automatic registration failed at authentication phase.  Unable to acquire access token.  Exit code: Unspecified error. Server error: AdalMessage: ADALUseWindowsAuthenticationTenant failed,  unable to preform integrated auth
AdalErrorCode: 0xcaa9002c

This error usually indicates an issue with connecting to AD FS farm. Check if Windows Integrated Authentication is enabled for Intranet, is working correctly for Intranet and WSTrust windows endpoints are enabled in AD FS.

Azure Multi-Factor Authentication Server with ADFS – EventID 105 troubleshooting. Part 2

You might already have checked for the EventID 105 error solution in my previous post.

This time the issue was similar, followed the official instructions – and when restarting the AD FS service we got the EventID 105.

Looking at the ADFS Debug logs see new error:
Log Name:      AD FS Tracing/Debug
Source:        AD FS Tracing
Date:          3/6/2018 3:03:41 PM
Event ID:      183
Task Category: None
Level:         Error
Keywords:      ExternalAuthentication
User:          XXX
Computer:      XXX
OnAuthenticationPipelineLoad() exception: System.Exception: Error connecting to Multi-Factor Authentication service. —> System.Runtime.InteropServices.SEHException: External component has thrown an exception.
   at native.construct(construct_ret_t* , __MIDL_pfAgent_idl_0009 )
   at PfSvcClientClr.PfSvcClient.construct(ConstructTarget target, ConstructResult& result)
   at pfadfs.AuthenticationAdapter.ConnectToService(ConstructTarget constructTarget, Int32 lcid)
   — End of inner exception stack trace —
   at pfadfs.AuthenticationAdapter.ConnectToService(ConstructTarget constructTarget, Int32 lcid)
   at pfadfs.AuthenticationAdapter.OnAuthenticationPipelineLoad(IAuthenticationMethodConfigData configData)
   at Microsoft.IdentityServer.Web.Authentication.External.ExternalAuthenticationHandlerBase.

Looking at MultiFactorAuthenticationAdfsAdapter.config file closer, have noticed that the value of UseWebServiceSdk is True, so have changed it to true, re-run the Registration script and there were no errors after AD FS service restart.

Discover and protect from crypto miners in your network using pfSense firewall

In a raise of popularity of crypto mining there is a shift in the threat landscape. Attackers “are beginning to recognize that they can realize all the financial upside of previous attacks, like ransomware, without needing to actually engage the victim and without the extraneous law enforcement attention that comes with ransomware attacks,” Talos researchers write in a new post( ).

One of the steps you can take to protect your network, is to block outgoing connection to the IP addresses associated with crypto mining pools. Those IPs are easy to get from SANS API (See for details).

I have used following PowerShell scrip to get the latest IP list.

$date = Get-Date -format "yyyyMMdd"
$url = ""
$membersList = Invoke-RestMethod -Uri $url
$membersList | select threatlist -ExpandProperty threatlist |
select miner -ExpandProperty miner | select ipv4 -ExpandProperty ipv4 |
Sort-Object ipv4 -Descending |
out-file "D:\Temp\miners$date.txt"

After that sign in your pfSense firewall, go to Firewall – Aliases menu.

pfSense Aliases menu allows bulk IP addresses upload. Press Import button on the bottom of Aliases page and use the content of the TXT file created earlier to create the alias for the IPs associated with crypto mining pools. I would recommend giving the alias meaningful name which includes the date of creation (will make the firewall rule and aliases management easier as you update the list).


After creating the alias, go to your LAN rules and create the rule to block any connection from your LAN network to the CryptoMining alias and make sure the rule is on the top of the list (right after rules allowing access to pfSense management ports). Optionally you can select log to monitor what stations in your network tried the malicious outbound connection.


On regular basis you can update the IP list and create the new alias (with new date in the name). After that you can easily update the firewall rule by simply changing the destination to new alias.

Also its always recommended to place a default block all LAN rule for outgoing traffic to make sure only authorized connections are successful to the Internet from your hosts.


How to replace the host name in captured Fiddler trace

For the previous post had to find out how to replace the host name in the captured Fiddler trace.

To do this, open the Fiddler, go to Rules – Customize Rules. The Fiddler ScriptEditor will open.

Use following code to create new column named MaskedHostName with new host names. You can put it right after commented (green) part of the script.

public static BindUIColumn("MaskedHostName", 60)
function FillNameColumn(oS: Session): String {
if (oS.hostname.EndsWith("")) return "”;
if (oS.hostname.EndsWith("")) return "”;
return oS.hostname;

 If some of your host names look similar (like “OtherHost1” and “Host1”) make sure you put the longer host name to the top of the list, so its evaluated first and you don’t have both host names replaced by “”

Federated applications (CRM and IIS) ADFS Single Sign-On (SSO) troubleshooting with Fiddler

Recently had very interesting issue to troubleshoot. This (long 😊 ) troubleshooting description for sure will help many to understand the ADFS Single Sign-On (SSO) flow and how to read the Fiddler traces.

Environment: ADFS 3.0, CRM 2013, IIS 8.5 running a site. Both the CRM and the IIS site are federated with the ADFS.

The CRM and the IIS site were accessed from outside of the corporate network, so only Form Based Authentication was taking place when redirected to the ADFS.

Problem: If the user accesses the IIS site first, completes authentication to the ADFS, then the user browses to the CRM site (using the same browser), the ADFS SSO takes place and user do not have to authenticate second time (put user name and password) via ADFS to access the CRM.

But if the user accesses the CRM first, completes authentication to the ADFS and then browses to the IIS site, the ADFS SSO doesn’t take place and the user is presented with the ADFS Form Based Authentication (FBA) page.

Another variable added to the puzzle was the fact that the CRM and the IIS belong to one Active Directory domain (lets call it EXTERNAL) and the ADFS belongs to other (call it PUBLIC). The two-way trust was configured between these domains. As troubleshooting continued, the issue was replicated if all three services (ADFS, CRM, IIS) were placed in the same AD, so the issue was NOT about on-premises AD location and which domain the services belonged to (more details explained below).

Troubleshooting: As always in such cases, the Fiddler trace was captured to get better understanding of browser redirections and sign in processes.

Here is a non-working SSO attempt (Note: in some screenshots I’m not able to show all the details (but will do my best to provide good description).


Frame #2 – user accesses the CRM and is redirected to the ADFS;

Frame #3-8 – user completes the ADFS FBA (providing correct username/password) and browser gets the ADFS SSO cookie – MSISAuth=AAEAAJo…;


Frame #9 – the ADFS redirects the browser with the ADFS SSO cookie to itself, where the ADFS SSO cookie is exchanged to the ADFS access token (MSISAuthenticated) that will be presented to the application as a proof that the user was authenticated;


Frame #10 – browser is redirected to the CRM Ws-Fed endpoint configured in the ADFS CRM Relying Party, where MSISAuthenticated cookie is exchanged to two application session cookies (MSISAuth=77uj… and MSISAuth=VWJ0…). These two cookies will always be presented to the CRM by browser as a proof that this is “authenticated” session;


Frame #13 – user opens a new tab in the browser and goes to the IIS site. The browser presents two CRM session cookies to the IIS site and obviously, the IIS site doesn’t recognize them and redirects the browser to the ADFS for authentication;


Frame #14 (were all fun begins) – The browser presents 3 cookies to the ADFS – the ADFS SSO cookie we got in Frame #8 + 2 CRM application cookies;


Looks like regardless correct ADFS SSO cookie presented (MSISAuth=AAEAAJo…), it was not accepted by the ADFS and the Form Based Authentication sign in page is returned. No errors in the ADFS Admin logs.

In the ADFS Debug logs see the following error:

Log Name:      AD FS Tracing/Debug
Source:        AD FS Tracing
Date:          2/6/2018 1:52:20 PM
Event ID:      67
Task Category: None
Level:         Error
Keywords:      ADFSProtocol
User:          S-1-5-21-1337953637-3591879799-2366245552-4020
Computer:      XXX
Ignore corrupted SSO cookie.

Have confirmed that this is expected ADFS 3.0 behavior to parse all cookies through its code pipe. Since the browser was presenting 2 cookies with the same name (MSISAuth – one set by the ADFS, other by the CRM) only the last one in the pipe was treated as the ADFS SSO cookie. But as we see from previous screenshot, the last cookie in the pipe was MSISAuth=77uj… and was set by CRM and for sure is not a valid ADFS SSO cookie.

When looking at the trace when we access the IIS site first and the CRM second, the issue with non-working SSO is NOT present, because the IIS site was setting cookies with the name of FedAuth and that cookie name is not causing the issue during the ADFS cookies evaluation.


Explained the above flow to the owner of the environment and said that the solution is to see if we can make sure the CRM is not using MSISAuth name for its session cookie.

After that, the owner of the environment added another variable to this puzzle . He said he has other CRM and IIS site federated with the same ADFS 3.0 farm, but there the issue we are troubleshooting is NOT present there!

Captured new Fiddler trace for working scenario.

Following screenshot is for working sign in.


The authentication flow is the same – user accesses CRM (#2), browser redirected to the ADFS, successfully authenticates (#3-8), the CRM WS-Fed endpoint sets the session cookies with name MSISAuth (#9-10), user opens new tab to the IIS site (#12), site redirects to the ADFS (#13).

But looking at the Frame #13 we see that the browser is sending ADFS only one MSISAuth cookie (the ADFS SSO cookie) which ADFS accepts and issues MSISAuthenticated cookie to the IIS site (SSO takes place to IIS).

Frame13Good signin

So now the question was – why in one scenario the browser presents 3 cookies (ADFS SSO + 2 app session cookies), in other only one ADFS SSO cookie.

You might have already noticed the difference in the scenarios. As mentioned at the beginning, it was NOT about the local AD and what Active Directory domains each of three services belong to.

The explanation was discovered in the Frame #10 where the CRM was setting the application cookies. Going to the Raw tab in the response window and viewing the frame in Notepad, gave the explanation.


The domain scope was set for the cookie by the CRM.

Since in non-working scenario, all three services (ADFS, CRM, IIS) are located in the same domain name space (, the browser was presenting the CRM cookies as well to the ADFS when redirected from the IIS site.

In the second scenario the CRM was specifying in the session cookies and because ADFS belong to, the browser was not presenting the CRM cookies with the ADFS SSO cookie when it was redirected from the IIS to the ADFS for authentication.


To resolve the issue, it was decided to move production ADFS host name to different domain name space than CRM and IIS by the owner of the described environment.

So far was not able to confirm with the CRM team if its possible to change the name of the session cookies or make sure the domain name is not specified (though think the last is not a valid option at all).