The Certificate Connector for Microsoft Intune is a vital component that allows administrators to issue and manage enterprise PKI certificates to endpoints managed by Microsoft Intune. The connector is installed on a Windows server with access to the on-premises Certificate Authority (CA). It is registered with Intune and can be used by any PKCS or SCEP device configuration profiles defined by Intune administrators.

Agent Certificate

When you install the Certificate Connector for Intune, a certificate issued by the Microsoft Intune ImportPFX Connector CA is automatically enrolled into the local computer certificate store of the server where the connector is installed. This certificate authenticates the connector to Intune and is valid for one year from the date of issuance. This certificate is automatically renewed in most cases. However, some configurations prevent this from happening.

Failed To Renew

Administrators may find event log errors with event ID 2 from the CertificateConnectors source in the Microsoft-Intune-CertificateConnectors operational event log with the following information.

Pki Create Service:

Failed to renew agent certificate

System.Security.Cryptography.CryptographicException: Access is denied.

Root Cause

Agent certificate renewal fails when the Certificate Connector for Intune is running under a service account that is not a member of the local administrators security group. You will not encounter this error if the connector services are running in the SYSTEM context, however.

Resolution

There are a few different ways to resolve this issue. Here are some options to consider.

Grant Admin Rights

Adding the service account under which the connector service runs will allow the agent certificate to renew automatically. However, this may not be desirable from a security perspective. To address this, administrators may temporarily grant local administrative access to renew the agent certificate, then revoke this permission once the certificate has been successfully renewed. However, this is a manual process that doesn’t scale well and requires annual administrative intervention.

Reinstall

Uninstalling and reinstalling the Certificate Connector for Intune will force a new certificate enrollment during the registration process. You can delete the old certificate after completing the installation.

Switch to SYSTEM

Changing from a service account to SYSTEM will also resolve this issue. However, it is not recommended to make these changes directly on the services themselves. Instead, administrators should remove and reinstall the Certificate Connector for Intune, selecting the SYSTEM option rather than the service account method.

Note: Using the SYSTEM account for the Certificate Connector for Intune should be avoided when using PKCS. Details here.

Summary

The Certificate Connector for Intune agent certificate renewal fails when the service is configured to run as a service account without local administrative rights. The best way to resolve this is to add the service account to the local administrators group on the server where the connector is installed. However, this isn’t always ideal. Although running the connector in the SYSTEM context is acceptable when using SCEP, it should be avoided when using PKCS. Administrators will have to accept the risk of the service account having local administrative rights or accept that they’ll have to reinstall the connector annually.

Additional Information

Certificate Connector for Intune Service Account and PKCS

Strong Certificate Mapping for Intune PKCS and SCEP Certificates

Intune Strong Certificate Mapping Error

Intune PKCS and SCEP Certificate Validity Period

Certificate Connector for Intune Failure

Certificate Connector for Intune Configuration Failed

Troubleshooting Intune Failed PKCS Request