Claude Code extension version 2.1.313 implanted with an SSH backdoor; Cursor estimates up to 5,000 developers affected
Une extension officielle du modèle Claude d'Anthropic a été piratée et a mis en danger jusqu'à 5 000 ordinateurs de développeurs, Anthropic n'a pas encore averti ses clients de cet incident
Security firm Phorion found that the Claude Code extension for VS Code-compatible editors had been tampered with; version 2.1.313 appeared on Open VSX and was listed on the Cursor extension marketplace for about 11 hours, and Cursor estimates that up to 5,000 developers may be affected. The tampered version inserts an immediately invoked function expression at the start of extension.js, which writes the attacker's SSH key into the user's authorized_keys as soon as Node loads the file, and actively connects to the attacker's server to establish a tunnel, reconnecting about every 60 seconds; it also achieves persistence via a macOS launch item, Linux cron, and a scheduled task named SysMon on Windows. It sends back the hostname, username, working directory, Git email, public IP, and the names of up to 40 environment variables that appear to be keys or cloud credentials.
The incident lists affected versions, indicators of compromise and cleanup commands, which developers using VS Code-compatible editors can use to check whether their machines have been implanted with a backdoor.