Trojanized Claude Code Extension Installs Persistent Backdoor on Developer Machines

A malicious version of Anthropic's Claude Code extension was distributed to developers to install persistent SSH backdoors on affected systems, according to Dark Reading, The Hacker News, BleepingComputer, Help Net Security, and GBHackers News. BleepingComputer reported that the compromised extension exposed up to 5,000 developers for approximately 11 hours on October 29. [1][2][3][4][9]

Help Net Security reported that researchers at macOS security firm Phorion discovered the tampered package, identified as version 2.1.313, on the Open VSX marketplace. BleepingComputer noted that the extension carried the version number 2.1 and was distributed through the Cursor extension marketplace. [3][4]

The Hacker News and Help Net Security both report that the extension attempted to establish a persistent SSH backdoor on affected machines. Help Net Security added that the compromised package also exfiltrated developer data to the attacker. [2][4]

Dark Reading reported that the incident was one of two serious security issues hitting the Cursor integrated development environment on the same day, highlighting risks for artificial intelligence development platforms. [1]