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

Always On VPN and Device Sharing

Always On VPN client configuration settings are typically deployed in the user’s context. However, this presents a unique challenge when sharing a single device with multiple users who have an Always On VPN profile assigned to them. By design, Windows designates only a single user profile on a shared device to be “always on”. When multiple users with assigned Always On VPN profiles share the same machine, it could yield unexpected results.

Auto Trigger Profile

When an Always On VPN profile is provisioned to a user, Windows records information about this profile in the registry. Specifically, the Always On VPN profile’s name and GUID are recorded, as well as the user’s Security Identifier (SID) and the path to the rasphone.pbk file that contains the Always On VPN profile.

Multiple Users

When a new user logs on to a shared device and receives their Always On VPN profile, Windows overwrites this existing data in the registry with the current user’s information. Each time this user logs on, their Always On VPN connection will establish automatically. Any other users with Always On VPN profiles configured on the same shared device will no longer connect automatically after this. The most recently deployed Always On VPN profile will be designated the “always on” profile.

Connect Automatically

In the above scenario, any user with an assigned Always On VPN profile on the shared device can take over the “always on” designation by opening the VPN connection properties and checking the “Connect automatically” check box.

When this happens, this user will now own the “always on” profile, and other users on the shared device will no longer connect automatically.

Workarounds

If multiple users share a single device requiring Always On VPN connectivity, you have a few options.

Intune

If you are deploying Always On VPN client configuration settings using Intune, you must use the Custom device configuration profile template. Specifically, as shown here, you must deploy your XML configuration file using the ./Device/Vendor/MSFT/VPNv2/ OMA-DM URI.

Unfortunately, the native Intune VPN template does not support deploying Always On VPN profiles in the “all users” context.

PowerShell

When using PowerShell, either natively or with SCCM or another software deployment tool, administrators can use my Always On VPN deployment PowerShell script with the -AllUserConnection parameter.

PowerON DPC

When using PowerON Platforms’ Dynamic Profile Configurator (DPC) to deploy Always On VPN client configuration settings using on-premises Active Directory or via Intune, no changes are required. DPC deploys Always On VPN user profiles in the “all users” context by default.

Additional Information

New-AovpnConnection.ps1 PowerShell Script on GitHub

PowerON Platforms’ Dynamic Profile Configurator (DPC)

Always On VPN DPC with PowerON Platforms’ DPC

Always On VPN DPC with Intune

In the past, I’ve written about PowerON Platforms’ Always On VPN Dynamic Profile Configurator (DPC), a software solution administrators can use to provision and manage Always On VPN client configuration settings using Active Directory and group policy. In addition to streamlining the deployment and management of Always On VPN client settings, DPC has many advanced features and capabilities to ensure optimal security, performance, and connection reliability.

Optimizations

Many settings required to fine-tune and optimize Always On VPN connections are not exposed in the Intune UI or XML. They must be configured by manipulating configuration files, setting registry keys, and running PowerShell commands. Much of this can be automated using Intune Proactive Remediation, but it is far from ideal. Administrators must configure Always On VPN using one method, then deploy optimizations using another. In addition, Proactive Remediation suffers from timing issues where some settings are not applied immediately, resulting in degraded or inoperable VPN connections until changes take effect.

Always On VPN DPC

Always On VPN DPC allows administrators to configure many advanced settings quickly and conveniently using the familiar Group Policy Management console (gpmc.msc). DPC dramatically reduces the administrative burden associated with Always On VPN client management. In addition, DPC enables many of these options by default, ensuring optimal security and reliable operation. Also, DPC immediately implements all configuration settings, eliminating the need to reboot to apply configuration changes.

Intune and ADMX

Historically, Always On VPN DPC could only be used when managing endpoints exclusively with Active Directory group policy. However, DPC can now be used with Microsoft Endpoint Manager/Intune thanks to a new feature that allows administrators to import custom ADMX and ADML administrative templates to Microsoft Endpoint Manager (MEM).

Note: This feature is in public preview at the time of this writing.

DPC and Intune

The combination of DPC and Intune brings with it many advantages. Using DPC with Microsoft Endpoint Manager/Intune offers administrators simplified deployment and many advanced features provided by Always On VPN DPC. In addition, customers who have deployed DPC on-premises can now migrate seamlessly to Microsoft Endpoint Manager/Intune management without giving up DPC’s valuable features.

Learn More

Enter your contact details in the form below for more information regarding Always On VPN DPC. Also, visit https://aovpndpc.com/ to register for a free Always On VPN DPC trial.

Additional Information

Always On VPN with Active Directory Group Policy

Introduction to Always On VPN DPC

Always On VPN DPC Advanced Features

Always On VPN DPC Video Demonstrations

What’s New in Always On VPN DPC v3.0

Always On VPN DPC Free Trial

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