Finding Microsoft VPN/PPTP with runZero

Last month, researcher Alex Nichols at Nettitude reported a vulnerability in Microsoft’s Windows VPN software that could allow for remote code execution or local privilege escalation by an attacker. This vulnerability lies in a use-after-free condition that can occur in the Point-to-Point Tunneling Protocol (PPTP) logic of Microsoft’s VPN software. It has existed for over 10 years and is present in most Windows releases dating back to Windows Server 2008 and Windows 7.

What is the impact?

Tracked as CVE-2022-21972 with a CVSS “high” score of 8.1, this vulnerability is reportedly only exploitable in Windows Server versions, not Windows Desktop deployments, due to configuration differences (see “Affected Versions”). Successful exploitation requires non-trivial effort, but once achieved, an attacker may attain remote code execution (RPC) or local privilege escalation (LPE) on the target.

Are updates available?

Microsoft has provided patches for all affected Windows versions in the May 2022 Patch Tuesday update. Admins should update systems, but take note that some folks are experiencing issues with VPN (and other services, including RDP) after applying the June 2022 Patch Tuesday updates.

How do I find vulnerable Windows VPN instances with runZero?

From the Service Inventory, use the following pre-built query to locate assets running Microsoft VPN software within your network which may need remediation:

_asset.protocol:pptp and protocol:pptp and pptp.vendor:microsoft

As always, any prebuilt queries are available from our Queries Library. Check out the library for other useful inventory queries.

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