Strong Certificate Mapping for Intune PKCS and SCEP Certificates

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With the October 2024 Intune update, Microsoft introduced support for strong certificate mapping for certificates issued by Intune via the Intune Certificate Connector. Enabling strong certificate mapping support in Intune is an important change for those organizations using Microsoft Intune to issue and manage certificates for their users and devices, as it resolves a critical implementation blocker.

Note: This post was updated to clarify that adding the {{OnPremisesSecurityIdentifier}} for PKCS certificates is not required. This variable is only used for SCEP certificates.

Background

In May 2022, Microsoft released security update KB5014754, which added functionality to domain controllers and enterprise issuing certification authority (CA) servers, allowing the Kerberos Key Distribution Center (KDC) to enforce strong certificate mapping. Specifically, with KB5014754 installed, issuing CAs now add the requesting principal’s Security Identifier (SID) to the certificate in a new certificate extension. Domain controllers can be configured to reject authentication requests using certificates that do not include this information.

Today, DCs with KB5014754 installed will still allow authentication without strong certificate mapping. However, Microsoft has stated they will begin enforcing strong certificate mapping in February 2025, with an option to disable it via the registry. Starting in September 2025, full enforcement will be mandatory.

Reference: https://support.microsoft.com/en-us/topic/kb5014754-certificate-based-authentication-changes-on-windows-domain-controllers-ad2c23b0-15d8-4340-a468-4d4f3b188f16

Limitation

The initial changes in KB5014754 applied only to online certificate templates, meaning those that build the subject name from Active Directory. However, deploying certificates with Intune using either PKCS or SCEP requires using an offline certificate template that allows the requestor to supply the subject name in the request. When using offline templates, a certificate is issued but does not embed the SID in the certificate. Using offline templates presents unique challenges to organizations moving to modern management with Intune and Entra ID.

Intune Changes

The October 2024 Intune update addresses this limitation by providing a method to include SID information in certificates using either SCEP or PKCS.

SCEP

To include the SID information in SCEP certificates, create or edit an existing SCEP device configuration policy and define a URI Subject Alternative Name (SAN) attribute with the value {{OnPremisesSecurityIdentifier}} as shown here.

PKCS

To include SID information in PKCS certificates, administrators must ensure the Intune Certificate Connector is updated to at least version 6.2406.0.1001. In addition, a registry setting must be enabled on the Intune Certificate Connector server.

On the server where the Intune Certificate Connector is installed, open the registry editor, navigate to HKLM\Software\Microsoft\MicrosoftIntune\PFXCertificateConnector, and change the value of EnableSidSecurityExtension to 1.

Optionally, administrators can update this setting at the command line by running the following PowerShell command.

Set-ItemProperty -Path ‘HKLM:\SOFTWARE\Microsoft\MicrosoftIntune\PFXCertificateConnector’ -Name EnableSidSecurityExtension -Value 1 -Force

Once complete, restart the Intune Certificate Connector server for the changes to take effect.

Certificates

SID information is added to certificates differently depending on which Intune device configuration policy type is used.

PCKS

PKCS certificates have the SID embedded in the certificate extension 1.3.6.1.4.1.311.25.2, as shown here.

SCEP

SCEP certificates have the SID embedded in the Subject Alternative Name (SAN) field in the format “tag:microsoft.com,2022-09-14:sid:<SID>” as shown here.

Migration

When making these changes to embed the SID in Intune-issued certificates in an existing Intune PKCS or SCEP configuration policy, the change will only affect certificates issued after the change is made. To update all certificate holders, you must create and deploy a new device configuration policy to targeted users or devices. Deleting the old profile (or ensuring it no longer applies) will remove the old certificate from the endpoint. If you’ve configured your Intune Certificate Connector to support revocation, the old certificate will also be revoked.

Entra Conditional Access

Entra Conditional Access certificates have included SID information since July 2023. More details here.

Intune Cloud PKI

The changes above will also work with certificates issued by Cloud PKI for Intune.

Other Cloud PKI Providers

Many other Cloud PKI providers, such as SCEPman and KEYTOS, already include the embedded SID in their certificates. Other cloud PKI providers may also include embedded SID. Consult your provider to confirm.

Additional Information

Microsoft Intune October 2024 Strong Certificate Mapping Update

Microsoft Intune Certificate Connector Strong Certificate Mapping Update for PKCS

Entra ID Conditional Access Certificates with SID Information Now Available

Implementing Strong Certificate Mapping in Microsoft Intune PKCS and SCEP Certificates

Certificate-Based Authentication Changes and Always On VPN

Microsoft Security Service Edge Now Generally Available

A few weeks ago, Microsoft announced the general availability of its Security Service Edge (SSE) offering, Global Secure Access (GSA). GSA encompasses Entra Internet Access, a cloud-based Secure Web Gateway, and Entra Private Access, a Zero Trust Network Access (ZTNA) solution for accessing private data and applications on-premises.

ZTNA vs. VPN

Entra Private Access will be a compelling alternative to traditional VPN solutions such as Windows Always On VPN. Where traditional VPNs grant the endpoint an IP address on the internal network, Entra Private Access provides more granular access and does not require the device to be directly connected to the network.

GSA Client

Administrators must install the GSA client on all endpoints using Entra Internet Access or Entra Private Access. Today, the client is available for Windows and Android devices. iOS and macOS clients are forthcoming.

Private Network Connector

The Entra Private Access solution relies on the Entra Private Network Connector. The Entra Private Network Connector is a software component installed on-premises that provides remote access connectivity. Previously, it was called the Azure AD Application Proxy. Essentially, it is the same technology extended to support TCP and UDP network access in addition to HTTP.

Limitations

Entra Private Access is the way of the future for secure remote access. However, today, there are still some important limitations associated with this technology.

Private DNS

Although Microsoft announced general availability for Entra Private Access, it still lacks the private DNS feature many organizations require to provide feature parity with their existing VPN. This feature is still in private preview at the time of this writing. Hopefully, Microsoft will release this feature soon.

Device Connection

Entra Private Access does not support device-based connections. This limits its capabilities for domain-joined devices. If your organization uses hybrid Entra join today, consider sticking with Always On VPN until you move to native Entra joined endpoints.

Licensing

Global Secure Access (Entra Private Access and Entra Internet Access) are included in the Microsoft Entra Suite license. More information about Entra licensing can be found here.

Additional Information

Microsoft Global Secure Access Now Generally Available

Microsoft Entra Global Secure Access (GSA) Overview

Microsoft Entra Security Service Edge (SSE) on the RunAs Radio Podcast

Microsoft Entra Plans & Pricing