Intune Certificate Connector Configuration Failed

Troubleshooting Always On VPN Error 691 and 812 – Part 2

The Microsoft Intune Certificate Connector must be deployed on-premises to provision and manage enterprise PKI certificates using Intune. The Intune Certificate Connector supports the deployment of SCEP, PKCS, PKCS imported certificates, or any combination of these. The connector can be configured to run under the SYSTEM account or optionally (and recommended) a domain service account. When using a service account, the service account must have permission to log on as a service on the server where the Intune Certificate Connector server.

Access is Denied

Even when all prerequisites are met, administrators may still find the installation of the Intune Certificate Connector fails with the following error message.

“Configuring Microsoft Intune Certificate Connector failed. No changes were made to Feature or Proxy settings. Please try again.”

“Unexpected Failure. Error: System.lnvalidOperationException: Cannot open PFXCertificateConnectorSvc service on computer ‘.’ System.ComponentModel.Win32Exception: Access is denied”

Workaround

After the connector installation fails, open the file explore and navigate to C:\Program Files\Microsoft Intune\PFXCertificateConnector\ConnectorUI. Right-click PFXCertificateConnectorUI.exe and choose ‘Run as administrator’.

Run through the connector installation wizard again, and it should install without issue.

To avoid this problem for future Intune Certificate Connector deployments, administrators can right-click the Intune Certificate Connector installer (IntuneCertificateConnector.exe) and choose ‘Run as administrator’.

Additional Information

Microsoft Intune Certificate Connector Configuration Failure (Part 1)

Microsoft Intune Certificate Connector Service Account and PKCS

Microsoft Intune Learning Resources for Always On VPN Admins

Microsoft Intune Certificate Connector Overview

Always On VPN May 2023 Security Updates

Hey, Always On VPN administrators! It’s the second Tuesday of the month, which means security updates for Windows have been released. This month’s batch includes an update to address a critical vulnerability likely to affect many Always On VPN implementations using Windows Server.

SSTP Vulnerability

CVE-2023-24903 documents a vulnerability on Windows Servers with the Routing and Remote Access Service (RRAS) configured to support Secure Socket Tunneling Protocol (SSTP) for VPN connections. This is a remote code execution (RCE) vulnerability that can be exploited when an attacker sends a specifically crafted malicious packet to the server. Administrators are encouraged to update as soon as possible.

Mitigation

SSTP is commonly used for Always On VPN user tunnels. However, if administrators have configured user tunnels using IKEv2, or are using the device tunnel only, consider blocking inbound TCP 443 at the edge firewall to prevent attacks from the Internet. In addition, if SSTP is not in use, consider disabling support for SSTP by opening an elevated PowerShell command window and running the following commands.

netsh.exe RAS set wanports device = “WAN Miniport (SSTP)” rasinonly = disabled ddinout = disabled ddoutonly = disabled maxports = 0

Restart-Service RemoteAccess -PassThru

Alternatively, SSTP can be disabled in the RRAS management console by following the steps below.

  1. Open the RRAS management console (rrasmgmt.msc).
  2. Expand the server.
  3. Right-click Ports.
  4. Choose Properties.
  5. Highlight WAN Miniport (SSTP).
  6. Click Configure.
  7. Uncheck Remote access connections (inbound only).
  8. Uncheck Demand-dial routing connections (inbound and outbound).
  9. Enter 0 in the Maximum ports field.
  10. Click Ok.

Additional Information

Windows SSTP Remote Code Execution Vulnerability (CVE-2023-24903)

May 2023 Security Updates for Windows Server 2016 (KB5026363)

May 2023 Security Updates for Windows Server 2019 (KB5026362)

May 2023 Security Updates for Windows Server 2022 (KB5026370)

Always On VPN RRAS and Stale Connections

Always On VPN Updates for RRAS and IKEv2

Always On VPN administrators may be familiar with an issue that affects Windows Server Routing and Remote Access Service (RRAS) servers, where many stale VPN connections appear in the list of active connections. The issue is most prevalent when using IKEv2, either for the Always On VPN device tunnel or the user tunnel. Typically, this does not cause problems, but some administrators have reported issues related to port exhaustion or failed IKEv2 connections when many stale connections are present. Stale connections happen so frequently that I created a PowerShell script to clean them up on the RRAS server. Restarting the RemoteAccess service or rebooting the server also clears stale connections.

Microsoft Fix

Thankfully, Microsoft has addressed these issues in Windows Server 2019 and Windows Server 2022 this month. An update is now available in the March 2023 security update that resolves this problem.

You can find more information about the updates here.

The update was not made available for Windows Server 2016, however. Organizations are encouraged to upgrade to Windows Server 2019 or later to address this problem.

Additional Information

Always On VPN Updates for RRAS and IKEv2

Always On VPN IKEv2 Load Balancing and NAT

Always On VPN and IKEv2 Fragmentation

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