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Always On VPN April 2024 Security Updates

Microsoft has released its security updates for April 2024. This month, a few vulnerabilities are potentially impacting Always On VPN administrators. Specifically, three updates address issues with the Windows Server Routing and Remote Access Service (RRAS). In addition, vulnerabilities affect the Remote Access Connection Manager (RasMan) service, affecting both VPN servers and clients.

RRAS

Windows Server Routing and Remote Access (RRAS) has three security updates available this month. All three are Remote Code Execution (RCE) vulnerabilities but require user interaction to exploit the vulnerability. All three updates are rated as Important.

CVE-2024-26179

CVE-2024-26200

CVE-2024-26205

RasMan

In addition to the vulnerabilities in RRAS, Microsoft announced numerous updates for vulnerabilities discovered in the Remote Access Connection Manager (RasMan) service. These vulnerabilities are related to information disclosure via buffer overruns. These updates affect both Windows RRAS servers and Windows Always On VPN clients. All updates are rated as Important.

CVE-2024-26207

CVE-2024-26211

CVE-2024-26217

CVE-2024-26255

CVE-2024-28900

CVE-2024-28901

CVE-2024-28902

Recommendations

While none of these vulnerabilities are critical, Always On VPN administrators are urged to update their affected systems soon.

Additional Information

April 2024 Security Updates

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by Richard M. Hicks on April 9, 2024  •  Permalink
Posted in Always On VPN, AOVPN, CVE, Enterprise, enterprise mobility, Hotfix, Infrastructure, Microsoft, Mobility, Operational Support, Remote Access, routing and remote access service, RRAS, Security, Security Update, Update, VPN, Vulnerability, Windows 10, Windows 11, Windows Server 2016, Windows Server 2019, Windows Server 2022
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Posted by Richard M. Hicks on April 9, 2024

https://directaccess.richardhicks.com/2024/04/09/always-on-vpn-april-2024-security-updates/

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

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by Richard M. Hicks on November 14, 2023  •  Permalink
Posted in Active Directory, administration, Always On VPN, AOVPN, authentication, CVE, EAP, Enterprise, enterprise mobility, Infrastructure, Microsoft, Mobility, network policy server, NPS, Operational Support, PEAP, Protected EAP, Remote Access, Security, Security Update, Update, user tunnel, VPN, Windows Server 2016, Windows Server 2019, Windows Server 2022
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Posted by Richard M. Hicks on November 14, 2023

https://directaccess.richardhicks.com/2023/11/14/always-on-vpn-november-2023-security-updates/

Always On VPN Disconnects in Windows 11

Always On VPN administrators migrating their endpoints to Windows 11 may encounter a scenario where Always On VPN randomly disconnects when the VPN profile is deployed using Microsoft Intune. The same configuration deployed to Windows 10 devices works reliably, however. In addition, Always On VPN profiles deployed using PowerShell (natively or with SCCM) or PowerON DPC do not experience this problem.

Troubleshooting

Administrators troubleshooting this issue will find the root cause is associated with the Always On VPN profiles being removed and replaced each time the device syncs with Intune. This occurs even if there are no changes to the configuration. Removing and replacing the Always On VPN profiles on each device sync is unnecessary, of course, but is also highly disruptive to connected users.

Intune and XML

The Intune team identified the issue, and a fix was made available in the August update. However, many of you have reported the issue persists with some Windows 11 clients after installing the latest updates. Further investigation indicates that although the issue has been resolved when using Intune and the native VPN device configuration profile template, the problem still occurs when using the Custom device configuration template.

Workaround

Microsoft is aware of the issues with deploying Always On VPN client configuration settings using XML in Intune, but there’s no indication when or if they will fix it. Until then, administrators have two options to address this problem.

Native VPN Template

When deploying Always On VPN client configuration settings to Windows 11 endpoints, use the native VPN device configuration template, as shown here.

Using the native VPN template does have some limitations, however. The following settings are not exposed using the native VPN template and can only be configured using XML.

XML

If you must use XML, I’ve had some success by ensuring the order of XML settings is exactly as Intune expects. Follow the steps below to confirm the XML settings order in your XML configuration file.

  1. Deploy your XML file with Intune.
  2. Run Get-VpnClientProfileXML.ps1 to extract the deployed XML settings.
  3. Compare the order of settings to your existing XML.
  4. Make changes to ensure all settings in your XML are in the same order as the extracted XML.
  5. Publish a new XML configuration file using Intune and test.

I’ll caution you that this workaround doesn’t always work reliably. Some customers report that this solved their problems entirely, while others have indicated it does not. My testing shows the same results. Let us know in the comments below if this works for you!

Additional Information

Always On VPN Windows 11 Issues with Intune

Always On VPN PowerShell Script Issues in Windows 11

4 Comments
by Richard M. Hicks on October 9, 2023  •  Permalink
Posted in Always On VPN, AOVPN, AovpnDPC, Application Filter, Azure AD Join, Azure VPN, Deployment, Device Management, device tunnel, DPC, Dynamic Profile Configurator, Endpoint Manager, Enterprise, enterprise mobility, InTune, MDM, MEM, MEMCM, Microsoft, Microsoft Endpoint Manager, Microsoft Intune, Mobility, OMA-DM, OMA-URI, Operational Support, PowerShell, ProfileXML, Remote Access, SCCM, System Center Configuration Manager, systems management, Traffic Filter, Update, user tunnel, VPN, Windows 11
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Posted by Richard M. Hicks on October 9, 2023

https://directaccess.richardhicks.com/2023/10/09/always-on-vpn-disconnects-in-windows-11/

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