CVE-2022-36436: Twisted VNC Authentication Proxy Authentication Bypass

CVE-2022-36436: Twisted VNC Authentication Proxy Authentication Bypass - Introduction - GRNET provides VNC access to their VMs, which uses the Twisted VNC Authentication Proxy (VNCAuthProxy). A security vulnerability was discovered that allows an attacker to bypass the proxy server’s authentication mechanism. - Vulnerability Details - The proxy server permits clients to select the "None" security type, allowing access without authentication. - The proxy server supports two security types but does not enforce the "VNC Authentication" security type. - Impact - Attackers can gain access to a shared VNC console or force disconnection, potentially leading to the execution of arbitrary commands in the victim’s authenticated shell. - Exploitation - The attacker can scan ports 5800–5899 for open ports and connect using a VNC client configured with the "None" security type. - Recommendation - Upgrade the Twisted VNC Authentication Proxy to version 1.2.0 or later. - Vulnerability Timeline - Vulnerability identified on July 5, 2022; temporary fix applied on July 11, 2022; vendor contacted on July 12, 2022; CVE ID assigned on July 25, 2022; fix released on July 29, 2022. - References - Links to the Twisted VNC Authentication Proxy repository, the commit containing the fix, and the CVE entry.

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CVE-2022-36436: Twisted VNC Authentication Proxy Authentication Bypass