Always On VPN Security Updates August 2024

Today is the second Tuesday of the month, so Windows Server administrators everywhere know what that means – it’s Update Tuesday! For Always On VPN administrators in particular there are a few security updates that affect Windows Server Routing and Remote Access (RRAS), which is a popular VPN server used to support Always On VPN implementations. While many of these updates address Remote Code Execution vulnerabilities, non are considered critical.

RRAS Updates

This month there are six vulnerabilities disclosed affecting Windows Server RRAS.

CVE-2024-38120 – Windows RRAS Remote Code Execution Vulnerability (Important)

CVE-2024-38121 – Windows RRAS Remote Code Execution Vulnerability (Important)

CVE-2024-38128 – Windows RRAS Remote Code Execution Vulnerability (Important)

CVE-2024-38130 – Windows RRAS Remote Code Execution Vulnerability (Important)

CVE-2024-38154 – Windows RRAS Remote Code Execution Vulnerability (Important)

CVE-2024-38214 – Windows RRAS Remote Code Execution Vulnerability (Important)

Additional Updates

In addition to the updates addressing vulnerabilities in Windows Server RRAS, there are also updates available for the Windows Network Address Translation (NAT), Windows Transport Layer Security (TLS), and Windows IP Routing Management snapin that could potentially impact Always On VPN deployments.

Recommendations

None of the security vulnerabilities disclosed this month are critical. Although the RRAS vulnerabilities are remote code execution, exploitation is unlikely. However, administrators are encouraged to update their systems as soon as possible.

Additional Information

Microsoft August 2024 Security Updates

Always On VPN October 2023 Security Updates

Once again, it’s time to patch! After several quiet months, there are a few crucial updates Always On VPN administrators will want to get deployed soon. Thankfully, the impact of the security updates related to Always On VPN is low this time, as there is only one Remote Code Execution (RCE) vulnerability, and it’s for a legacy protocol that should be in limited use today.

IKEv2

CVE-2023-36726 addresses a security vulnerability in Windows Internet Key Exchange (IKE) that can lead to privilege escalation. An attacker who successfully exploits this vulnerability can elevate privileges to that of the local SYSTEM.

L2TP

This month’s update discloses several Layer Two Tunneling Protocol (L2TP) vulnerabilities. The following CVEs all address a vulnerability where an attacker can send a specially crafted protocol message to a Windows Routing and Remote Access Service (RRAS) server, which could lead to remote code execution on the server.

Mitigation

The impact of the L2TP security vulnerabilities should be minimal in most organizations. L2TP is a legacy VPN protocol not commonly used for Always On VPN. However, misconfiguration can leave vulnerable RRAS servers exposed. Administrators must ensure that inbound UDP port 1723 is not open from the Internet. In addition, L2TP should be disabled on the RRAS server if not in use. See the article on the May 2023 security updates for details.

Additional Information

October 2023 Security Updates

Always On VPN July 2023 Security Updates

Hello, Always On VPN administrators! It’s the second Tuesday of the month, so you know what that means. Yes, it’s Patch Tuesday! This month’s security updates include several fixes for vulnerabilities potentially affecting Microsoft Always On VPN deployments.

RRAS Vulnerabilities

Microsoft’s July 2023 security updates include fixes affecting Windows Servers with the Routing and Remote Access Service (RRAS) role installed. Security vulnerabilities CVE-2023-35365, CVE-2023-35366, and CVE-2023-35367 are all Remote Code Execution (RCE) vulnerabilities with a Critical security rating and a CVSS score of 9.8. These security vulnerabilities in Windows Server RRAS are particularly troublesome due to the nature of the workload. RRAS servers are, by design, exposed to the public Internet. Although there are no known exploits in the wild at this time, this attack requires no special privileges other than network access. Administrators running Windows Server with RRAS installed are encouraged to update as soon as possible.

AD CS Vulnerabilities

Most Always On VPN implementations leverage enterprise PKI certificates for user and device authentication. Administrators commonly deploy Microsoft Active Directory Certificate Services (AD CS) to support this. This month there are two security vulnerabilities in AD CS marked as Important. CVE-2023-35350 and CVE-2023-35351 address RCE vulnerabilities that exploit a race condition on the server. However, AD CS servers are not exposed to untrusted networks. In addition, attackers would require administrative rights on the server to exploit these vulnerabilities.

Network Load Balancing

Finally, of importance to Always On VPN administrators using Windows Network Load Balancing (NLB) to provide load balancing for their RRAS servers, there is a vulnerability in the NLB service. CVE-2023-33163 addresses an RCE vulnerability in NLB identified as Important.

Additional Information

Microsoft July 2023 Security Updates

Windows Server 2022 KB5028171 (Build 20348.1850)

Windows Server 2019 KB5028168 (Build 17763.4645)

Windows Server 2016 KB 5028169 (Build 14393.6085)

Windows 11 22H2 KB8028185 (Build 22621.1992)

Windows 11 21H2 KB5028182 (Build 22000.2176)