Backdoor in Claude Code for VS Code extension on the Cursor Marketplace

A backdoor has been discovered in the Claude Code for VS Code extension, available on the Cursor Marketplace. The malicious code establishes an SSH tunnel to 'localhost:22' and implements persistence mechanisms across Linux, macOS, and Windows. On Linux, it creates a shell script and adds an '@reboot' entry to crontab, with a bug that could wipe existing cron jobs. macOS uses a LaunchAgent, while Windows attempts a scheduled task named SysMon or falls back to the Startup folder.

This report details the specific persistence mechanisms used by the Claude Code for VS Code extension's backdoor across different operating systems, unlike general alerts that only mention its presence.