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

Always On VPN November 2023 Security Updates

Microsoft has released its security updates for November 2023. For Always On VPN administrators, it’s a light month, with just a single CVE affecting Always On VPN infrastructure.

PEAP

CVE-2023-36028 addresses a remote code execution (RCE) vulnerability in the Microsoft Protected Extensible Authentication Protocol (PEAP). An attacker could exploit this vulnerability by sending a specially crafted PEAP packet to a Windows Network Policy Server (NPS). This attack does not require authentication or user interaction.

Affected Systems

This PEAP vulnerability affects only NPS servers configured to support PEAP authentication explicitly. PEAP authentication is a best practice configuration for Always On VPN deployments and is widely deployed. NPS servers deployed to support other services, such as Wi-Fi or router and switch access that are configured to allow PEAP authentication, are also affected.

Exposure

NPS servers are not (or should not be!) exposed directly to the public Internet. This limits the attack surface to adversaries already on the internal network.

Mitigation

Microsoft suggests disabling PEAP authentication support on NPS servers until the update is applied. However, this would break the majority of Always On VPN deployments today. Since disabling PEAP isn’t a viable option, administrators can reduce their attack surface by updating the NPS firewall rules to restrict access only to authorized VPN servers or other network devices until their systems are fully updated.

Additional Information

November 2023 Security Updates

CVE-2023-36028 PEAP Remote Code Execution Vulnerability

Always On VPN and the PSPKI PowerShell Module

Certificates are a crucial part of a secure Always On VPN implementation. Certificates are phishing-resistant forms of authentication that, when configured correctly, provide robust and multifactor authentication for remote access users and devices.

AD CS

Most commonly, certificates are issued by an on-premises Microsoft Active Directory Certificate Services (AD CS) server. Administrators configure and deploy a Certification Authority infrastructure to issue and manage user and device authentication certificates in their organization. CA certificates are also required on the VPN server to support Always On VPN device tunnel connections and IKEv2 user tunnel connections. The NPS server also requires an enterprise CA certificate. Of course, the CA can issue certificates for other purposes, including Wi-Fi authentication, document signing, and code signing, just to name a few.

PSPKI

PSPKI is a PowerShell module available in the PowerShell Gallery for configuring, managing, and troubleshooting Microsoft AD CS. Created by Vadims Podans of PKI Solutions, PSPKI includes over 100 functions for various AD CS and certificate-related tasks. Always On VPN administrators will find this PowerShell module helpful when configuring and troubleshooting certificate-related issues for their Always On VPN deployments.

Note: The AD CS remote server administration tools (RSAT) must be installed to access all of the PSPKI module’s functionality.

Installation

Run the following PowerShell command to install the PSPKI PowerShell module.

Install-Module -Name PSPKI

Always On VPN and PSPKI

Always On VPN Administrators will immediately find a few PSPKI functions helpful when implementing and supporting Always On VPN.

Test-WebServerSSL – This function will connect to a remote web server and display details about the TLS certificate included in the response. This can be especially helpful when troubleshooting SSTP VPN connections.

Convert-PfxToPem – This is a handy utility for converting a PFX file to the PEM format. This is commonly required when importing CA certificates on non-Microsoft platforms, security devices, and load balancers.

Convert-PemToPfx – Occasionally, administrators must convert a certificate and private key in PEM format to PFX to install on a Windows server. This tool allows administrators to perform this task easily.

Get-CertificationAuthority – This function quickly enumerates all enterprise CA servers and displays information about their hostname, accessibility, service status, and type.

Ping-ICertInterface – This function helps troubleshoot CA connectivity issues. Administrators can quickly determine if a CA is reachable and capable of issuing a certificate using this command.

Get-CaTemplate – This command displays a list of certificate templates published on the specified target CA server. The certificate template’s display name and the minimum support CA version are provided. In addition, the output indicates if certificate autoenrollment is enabled on the template.

Much More

The PSPKI PowerShell module for AD CS has many tools for configuring and managing AD CS. PSPKI recently received a major update to version 4.0. Download and install PSPKI today. It will make your life easier, I can assure you!

Additional Information

PSPKI PowerShell Module – PowerShell Gallery

PSPKI PowerShell Module – GitHub

AOVPNTools PowerShell Module – PowerShell Gallery

AOVPNTools PowerShell Module – GitHub

InboxAccountingDatabaseManagement PowerShell Module

InboxAccontingDatabaseManagement – PowerShell Gallery

InboxAccountingDatabaseManagement – GitHub