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Intel Drop 24 | Trojanised Claude Code extension plants SSH backdoors via Cursor

intel-drop · TLP:CLEAR · 1 Nov 2026 · Risk 12/25 (L3 × I4)

T1195.002T1082T1098.004T1572T1053.005T1543.001

For about 11 hours on 29 Oct, tampered builds 2.1.312 and 2.1.313 ran on load, added an attacker SSH key (“svc-telemetry”), opened reverse SSH tunnels and persisted via a “SysMon” task or an Apple-named LaunchAgent. The actor is unknown.

Companion hunt: Hunt Drop 8.

Attack chain

  1. Tampered v2.1.312 / 2.1.313 served by the marketplace (T1195.002)
  2. Runs on load and profiles the host, Git email and env-var names (T1082)
  3. Adds the “svc-telemetry” key to authorized_keys (T1098.004)
  4. Reverse SSH tunnel to the attacker host, retrying about every 60 s (T1572)
  5. Persists as a “SysMon” task or a fake Apple LaunchAgent (T1053.005, T1543.001)

Risk

12/25 HIGH (likelihood 3 × impact 4), organisations with developers using Cursor.

Confidence

Assessment Confidence
Malicious activity HIGH
Actor attribution NONE (unknown)
Delivery path LOW (unexplained)

Business risk

The attack went after engineers: their laptops and their tools sit one step away from money, code and cloud.

What to do now

  • Check authorized_keys for “svc-telemetry” and rotate exposed credentials.
  • Allow-list and pin IDE extensions.

Sources

  1. Cursor security notice (29 Oct 2026, upd. 30 Oct): https://cursor.com/blog/claude-code-extension-security-notice
  2. Help Net Security (30 Oct 2026): https://www.helpnetsecurity.com/2026/10/30/claude-code-extension-ssh-backdoor/
  3. The Register (30 Oct 2026): https://www.theregister.com/cyber-crime/2026/10/30/anthropic-that-claude-code-extension-compromise-couldnt-be-us/5306682
  4. Cyber Security News (31 Oct 2026): https://cybersecuritynews.com/malicious-claude-code-extension-with-cursor/