All posts in category Azure Conditional Access

Azure Conditional Access Certificates with SID Information Now Available

I recently wrote about changes to certificate-based authentication affecting Always On VPN implementations. These changes were introduced by Microsoft’s security update KB5014754. When the update is installed on domain controllers and enterprise Certification Authorities (CAs), administrators can perform strong user mapping for certificates used for Active Directory authentication. However, when first introduced, the update came with some serious limitations that prevented administrators from enabling full enforcement mode for certificate mapping.

Limitations

When KB5014754 is installed on an enterprise issuing CA, a new certificate extension (1.3.6.1.4.1.311.25.2) is added to the issued certificate that includes the principal’s (user or device) Security Identifier (SID). However, this only occurs when an online template is used. An online template is one with the subject name built from Active Directory information. The SID is not embedded in certificates issued using an offline template. Offline templates are templates where the subject name is supplied in the request. There are two scenarios where this causes problems for Always On VPN.

Microsoft Intune

Certificates delivered with Microsoft Intune via the Intune Certificate Connector use an offline template. This applies to certificates using PKCS or SCEP. Today, the SID is not embedded by issuing CAs using offline templates.

Azure Conditional Access

The short-lived certificate issued by Azure when Conditional Access is configured for Always On VPN did not include the SID. However, that recently changed.

Recent Updates

Today we can scratch Azure Conditional Access off the list of limitations for Always On VPN. Microsoft recently introduced support for the new SID extension in Azure Conditional Access certificates, as shown here.

Now when an Azure Conditional Access certificate is issued to an on-premises user or device account that is synced with Azure Active Directory, Azure Conditional Access will include the SID information in the issued short-lived certificate.

Intune

Unfortunately, we’re still waiting for Microsoft to address the limitation with certificates delivered using Microsoft Intune. Hopefully we’ll see an update for that later this year.  

Additional Information

Certificate-Based Authentication Changes and Always On VPN

Microsoft KB5014754

Digital Certificates and TPM

Microsoft Intune Certificate Connector Service Account and PKCS

3 Comments
by Richard M. Hicks on July 11, 2023  •  Permalink
Posted in AADJ, Active Directory, administration, Always On VPN, AOVPN, authentication, Azure, Azure Active Directory, Azure AD, Azure AD Join, Azure Conditional Access, Azure MFA, Azure VPN, Certificate Connector for Intune, certificates, cloud, Conditional Access, Deployment, Device Management, Endpoint Manager, Enterprise, enterprise mobility, HAADJ, Hybrid Azure AD Join, Infrastructure, InTune, Intune Certificate Connector, Intune PFX Connector, MDM, MEM, MEMCM, MFA, Microsoft, Microsoft Endpoint Manager, Microsoft Intune, Mobile Device Management, Mobility, Multifactor Authentiction, NDES, Network Device Enrollment Service, Network Device Enrollment Services, NPS, Operational Support, PFX Connector, PKCS, PKI, public cloud, public key infrastructure, Remote Access, SCEP, Security, Simple Certificate Enrollment Protocol, systems management, Update, user tunnel, VPN, Windows 10, Windows 11
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Posted by Richard M. Hicks on July 11, 2023

https://directaccess.richardhicks.com/2023/07/11/azure-conditional-access-certificates-with-sid-information-now-available/

Always On VPN Book Available for Pre-Order

Great news! My new book, Implementing Always On VPN, is now available for pre-order on Amazon.com. This new book, scheduled for release in late 2021, is a comprehensive implementation guide for Windows 10 Always On VPN. Drawing on many years of experience deploying Always On VPN for organizations worldwide, it covers all aspects of an Always On VPN deployment, including planning and design, prerequisite gathering, infrastructure preparation, and client deployment.

In addition, it contains detailed, prescriptive guidance for advanced configuration options such as application and traffic filtering and proxy server configuration. Cloud deployments using Azure VPN gateway and Virtual WAN are covered, and it includes guidance for configuring Azure MFA and Conditional Access.

Also, the book includes thorough guidance for provisioning certificates using Microsoft Endpoint Manager/Intune using both PKCS and SCEP. It outlines options for high availability for VPN and authentication infrastructure and provides details for ongoing system maintenance and operational support.

Finally, the book has an entire chapter dedicated to troubleshooting and resolving common (and not so common!) issues encountered with Windows 10 Always On VPN.

Reserve your copy today. Pre-order Implementing Always On VPN now!

Chapter List

  1. Always On VPN Overview
  2. Plan an Always On VPN Deployment
  3. Prepare the Infrastructure
  4. Configure Windows Server for Always On VPN
  5. Provision Always On VPN clients
  6. Advanced Configuration
  7. Cloud Deployments
  8. Deploy Certificates with Intune
  9. Integrating Azure MFA
  10. High Availability
  11. Monitor and Report
  12. Troubleshooting
5 Comments
by Richard M. Hicks on September 27, 2021  •  Permalink
Posted in Always On VPN, Always On VPN Book, AOVPN, AOVPN Book, authentication, Azure, Azure Active Directory, Azure AD, Azure Conditional Access, Azure MFA, Azure Virtual WAN, Azure VPN, Azure VPN Gateway, certificates, cloud, Conditional Access, Device Management, device tunnel, education, Endpoint Manager, Enterprise, enterprise mobility, High Availability, InTune, Intune Certificate Connector, Intune PFX Connector, learning, Load Balancing, MFA, Microsoft Endpoint Manager, Microsoft Intune, Mobility, Multifactor Authentiction, NDES, Network Device Enrollment Services, network policy server, NPS, Operational Support, PFX Connector, PKI, PowerShell, ProfileXML, public cloud, public key infrastructure, Recommended Reading, Remote Access, reporting, routing and remote access service, RRAS, SCCM, SCEP, Security, Simple Certificate Enrollment Protocol, System Center Configuration Manager, systems management, Traffic Filter, user tunnel, VPN, Windows 10, Windows 11, Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, Windows Server 2022, Zero Trust, Zero Trust Network Access, ZTNA
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Posted by Richard M. Hicks on September 27, 2021

https://directaccess.richardhicks.com/2021/09/27/always-on-vpn-book-available-for-pre-order/

Always On VPN Authentication Failure with Azure Conditional Access

Always On VPN Clients Prompted for Authentication when Accessing Internal Resources

Integrating Microsoft Azure Conditional Access with Windows 10 Always On VPN has several important benefits. The most important is that it allows administrators to improve their security posture by enforcing access polices that can be dynamically applied. For example, requiring multifactor authentication (MFA) for privileged users (e.g., administrators) or sign-ins that appear to be risky, the type of device they are connecting with, the health of the endpoint, and much more.

Authentication Failure

When configuring Always On VPN to support Azure Conditional Access, administrators may expeirence a failed authentication during preliminary testing. Specifically, an event ID 20227 from the RasClient source may be encountered with the following error message.

“The user <username> dialed a connection named <connection name> which has failed. The error code returned on failure is 812.”

Looking at the event logs on the Network Policy Server (NPS) server reveals an event ID 6273 from the Microsoft Windows security auditing source with Reason Code 258 and the following Reason.

“The revocation function was unable to check revocation for the certificate.”

Root Cause

When Azure Conditional Access is configured for Always On VPN, a short-lived certificate (1 hour lifetime) is provisioned by Azure. This certificate does not include revocation information because, by design, a short-lived certificate does not need to be revoked. However, by default NPS always checks revocation when client authentication certificates are used for authentication. Since the certificate does not include this information, certificate revocation fails.

Resolution

The way to resolve this issue is to disable certificate revocation checking for Protected Extensible Authentication Protocol (PEAP) authentication requests. To do this, open an elevated PowerShell window on the NPS server and run the following command.

New-ItemProperty -Path ‘HKLM:\SYSTEM\CurrentControlSet\Services\RasMan\PPP\EAP\13\’ -Name IgnoreNoRevocationCheck -PropertyType DWORD -Value 1 -Force

Once complete, restart the NPS server for the changes to take effect.

Additional Information

Windows 10 Always On VPN Network Policy Server (NPS) Load Balancing

Windows 10 Always On VPN Network Policy Server (NPS) Server 2019 Bug

24 Comments
by Richard M. Hicks on August 29, 2021  •  Permalink
Posted in Always On VPN, AOVPN, Azure, Azure Active Directory, Azure AD, Azure Conditional Access, Azure MFA, Azure VPN, Azure VPN Gateway, certificates, Conditional Access, EAP, Enterprise, enterprise mobility, HAADJ, Hybrid Azure AD Join, MFA, Mobility, Multifactor Authentiction, network policy server, NPS, Operational Support, PowerShell, Protected EAP, Remote Access, RRAS, user tunnel, VPN, Windows 10
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Posted by Richard M. Hicks on August 29, 2021

https://directaccess.richardhicks.com/2021/08/29/always-on-vpn-authentication-failure-with-azure-conditional-access/

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