[Cursor Extension Store Poisoned: Claude Code Implanted with SSH Backdoor, Affecting Up to 5,000 Users] Beating AI News reports that Cursor disclosed on October 29th that a maliciously modified version of Claude Code 2.1.313 appeared in its extension store. This installer was not created by Anthropic and was available in the store for approximately 11 hours. Cursor estimates that up to 5,000 users are affected and will contact them directly. Security research firm OpenSourceMalware analysis revealed that attackers inserted 66 lines of malware before the plugin's normal code. The code executes whenever the extension is loaded in the editor, even without the user interacting with Claude. The malware collects information such as computer name, Git email address, and public IP address, and also secretly adds the attacker's keys to the SSH authorization list. The attacker then attempted to enable remote login, connecting to the attacker's server via a reverse SSH tunnel and setting up a background task to run automatically at startup, reconnecting approximately every 60 seconds. However, the attack code itself contained errors. Cursor stated that most Mac and Windows computers do not grant it the administrator privileges required to enable SSH service, so the attacker typically cannot log in through the tunnel. However, adding malicious keys, installing background scripts, and sending device information can still be successful. Computers already with SSH service enabled cannot be considered secure. Cursor has removed the malicious version, temporarily shut down its entire extension marketplace, and assisted in shutting down the attacker's server. Affected users need to check their SSH license files for the presence of `svc-telemetry` and use the official fix script to remove it. Simply uninstalling the extension is not enough; the background backdoor may continue to operate. [Original Link]