Microsoft Entra Global Secure Access

Last week Microsoft introduced new Security Service Edge (SSE) capabilities as part of the Microsoft Entra suite of technologies. Included in these announcements, Microsoft introduced the public preview of two new secure remote access technologies – Microsoft Entra Internet Access and Microsoft Entra Private Access. The latter of these will particularly interest Microsoft Always On VPN administrators in some deployment scenarios.

Microsoft Entra Internet Access

Microsoft Entra Internet Access is a new Secure Web Gateway (SWG) cloud service solution designed to protect users from threats on the public Internet. Features include web content filtering, malware inspection, TLS inspection, and more. In addition, Entra Internet Access can protect Microsoft 365 applications. Azure Conditional Access policies can be enforced for Internet traffic. Network conditions are now included with Azure Conditional Access, which can further protect against attacks by requiring access from specific trusted or compliant networks. Today, the public preview is available for Microsoft 365 scenarios only. Internet traffic and other SaaS applications will be available later this year.

Microsoft Entra Private Access

Microsoft Entra Private Access is a Zero Trust Network Access (ZTNA) cloud service solution that leverages the Azure Application Proxy access model. With Azure App Proxy, administrators can easily publish private, on-premises web applications by installing the connector on an on-premises server. Administrators can leverage Azure AD authentication and conditional access policies to ensure device compliance or enforce multifactor authentication (MFA), if required. Microsoft Entra Private Access extends the capabilities of the Azure Application Proxy to support TCP and UDP-based applications.

Private Access vs. Always On VPN

Microsoft Entra Private Access will be a compelling alternative to Always On VPN in the future. Specifically, organizations using native Azure AD join devices could benefit tremendously from this technology. Microsoft Entra Private Access is much simpler to implement than Always On VPN and requires no on-premises infrastructure other than the Azure Application Proxy connector. Using Microsoft Entra Private Access also means that no inbound access from the Internet is required, making the solution inherently more secure and reducing the public attack surface. For organizations using hybrid Azure AD join, Always On VPN continues to be the best Microsoft solution for these scenarios.

References

Microsoft Entra Expands into Security Service Edge (SSE)

Microsoft Entra – Secure Access for a Connected World

Microsoft Entra Internet Access Preview

Microsoft Entra Private Access Preview

What is Zero Trust?

What is Zero Trust Network Access?

What is Security Service Edge (SSE)?

What is Secure Access Service Edge (SASE)?

What’s the Difference Between SSE and SASE?

Contact Us

I’ve had the privilege of participating in the private preview for Microsoft Entra Internet Access and Private Access. If you’d like to learn more about these technologies and how they can help your organization, fill out the form below, and I’ll provide more information.

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 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