All posts tagged Patch Tuesday

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

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by Richard M. Hicks on October 10, 2023  •  Permalink
Posted in Always On VPN, AOVPN, Enterprise, enterprise mobility, Hotfix, IKEv2, Infrastructure, Microsoft, Mobility, Operational Support, Remote Access, routing and remote access service, RRAS, Security, Security Update, user tunnel, VPN, Windows 10, Windows 11, Windows Server 2016, Windows Server 2019, Windows Server 2022
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Posted by Richard M. Hicks on October 10, 2023

https://directaccess.richardhicks.com/2023/10/10/always-on-vpn-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)

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by Richard M. Hicks on July 11, 2023  •  Permalink
Posted in Active Directory, Active Directory Certificate Services, AD CS, administration, Always On VPN, AOVPN, Certificate Services, certificates, CVE, Deployment, Device Management, Enterprise, enterprise mobility, Hotfix, Infrastructure, Load Balancing, Microsoft, Mobility, Operational Support, PKI, public key infrastructure, 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 July 11, 2023

https://directaccess.richardhicks.com/2023/07/11/always-on-vpn-july-2023-security-updates/

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)

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by Richard M. Hicks on May 9, 2023  •  Permalink
Posted in administration, Always On VPN, AOVPN, device tunnel, Enterprise, enterprise mobility, IKEv2, Infrastructure, Microsoft, Mobility, Operational Support, PowerShell, Remote Access, routing and remote access service, RRAS, Secure Socket Tunneling Protocol, Security, SSTP, TLS, Update, user tunnel, VPN, Windows 10, Windows 11, Windows Server 2016, Windows Server 2019, Windows Server 2022
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Posted by Richard M. Hicks on May 9, 2023

https://directaccess.richardhicks.com/2023/05/09/always-on-vpn-may-2023-security-updates/

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