Overview
- A modified Claude Code extension (v2.1.313) was published through Cursor’s VS Code marketplace and was available for roughly 11 hours on October 29, during which it could auto-update into users’ editors.
- Security researchers found a 66-line loader that ran at extension load, collected host inventory data, appended an attacker SSH key labeled svc-telemetry, attempted to enable SSH, opened a reverse SSH tunnel to 134.209.82.225, and installed cross‑platform persistence.
- Cursor removed the malicious package, temporarily took down and rebuilt its marketplace, rotated keys, worked with the hosting provider to take the attacker server offline, and pushed a clean release (v2.1.314) while notifying affected users.
- At most 5,000 users may have installed the tampered release; coding errors in the loader likely prevented SSH activation on many macOS and Windows hosts but did not stop key planting, persistence or beaconing of environment-variable names.
- Users are advised to check for the svc-telemetry key, remove platform persistence (LaunchAgent, cron @reboot, Windows scheduled task), isolate affected hosts, rotate credentials from a clean machine, and consider hash‑pinning and stricter auto‑update governance to reduce supply‑chain risk.