Microsoft Intune Certificate Connector Failure

The Microsoft Intune Certificate Connector enables the provisioning and de-provisioning of on-premises PKI certificates for Intune-managed devices. Always On VPN administrators using Intune to deploy certificates with the Intune Certificate Connector using either PKCS or SCEP may encounter a scenario where certificates are no longer being provisioned to users or devices after working reliably previously.

Certificate Not Found

When this issue occurs, users will no longer be able to access the VPN and receive a “certificate could not be found that can be used with this Extensible Authentication Protocol” error message.

Connector Status

To determine the status of the Intune Certificate Connector, open the Microsoft Intune Admin Center (https://intune.microsoft.com) and navigate to Tenant Administration > Connectors and Tokens > Certificate Connectors. The status of the certificate connector server will be in Error.

Event Log

Open the event log on the server where the Intune Certificate Connector is installed. Navigate to Applications and Services Logs > Microsoft > Intune > CertificateConnectors > Operational. Here, you will find a variety of warning and error messages.

Event ID 5001

This is a warning from the CertificateConnectors source with event ID 5001 in the Task Category HealthMessageUploadFailedAttempt with the following details.

PKI Create Service:

Failed to upload health messages. Requeuing messages.

Event ID 1003

This is an error from the CertificateConnectors source with event ID 1003 in the Task Category PkcsDownloadFailure with the following details.

PKI Create Service:

Failed to download PKCS requests.

Event ID 2

This is an error from the CertificateConnectors source with event ID 2 in the Task Category Exception with the following details.

PKI Create Service:

Microsoft.Intune.Connectors.PkiCreateProcessor.Process threw an exception.

Expired Certificate

The warning and error messages recorded in the event log indicate an expired certificate on the Intune Certificate Connector server. Open the local computer certificate store (certlm.msc) on the server where the Intune Certificate Connector is installed. Review the expiration date of the certificate issued by Microsoft Intune ImportPFX Connector CA. It is most likely expired.

Click on the Certification Path tab to view the certificate status.

Renew Certificate

To renew this certificate, you must reinstall the Intune Certificate Connector. However, you do not have to uninstall it first. To renew the certificate, navigate to C:\Program Files\Microsoft Intune\PFXCertificateConnector\ConnectorUI and double-click on PFXCertificateConnectorUI.exe. Follow the prompts without making changes to the existing configuration. You’ll be prompted for the service account password (if using a domain account) and proxy credentials (if using a proxy server). In addition, you’ll be asked to sign in to Entra ID (formerly Azure AD). Be sure to provide credentials that are a global administrator and have an Intune license assigned. Once the process is complete, a new certificate will be installed in the local computer certificate store.

Intune Configuration

After updating the Intune Certificate Connector, a new certificate connector appears in the Intune Admin Center. You can now safely delete the old connector and rename the new one accordingly.

Redundancy

Deploying multiple instances of the Intune Certificate Connector is an excellent way to avoid future outages! It’s also a good idea to stagger their installation by a few months to ensure that a future certificate expiration doesn’t result in lost functionality. If you’ve deployed Intune Certificate Connectors recently, consider updating them at rotating intervals so certificates expire at different times.

Additional Information

Intune Certificate Connector Configuration Failed

Intune Certificate Connector Service Account and PKCS

Intune Certificate Connector Configuration Failure

Microsoft Intune Learning Resources for Always On VPN Administrators

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