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Malicious Claude Code VS Code extension installed persistent SSH backdoor

techOct 30, 202653184

A maliciously modified Claude Code VS Code extension release, version 2.1.313, installed a persistent SSH backdoor on machines that installed it. Cursor, the coding-tool company owned by SpaceX, said up to 5,000 users may have been affected and removed the tampered 2.1.313 build from its marketplace; investigators traced the compromise to Cursor’s marketplace and Open VSX records. Security researcher Phorion and multiple threat reports found the trojanized bundle added an SSH key, created persistence across macOS, Linux, and Windows, and exfiltrated host details before Anthropic published a clean 2.1.314 replacement. Socket’s analysis reported no record of that specific version on other registries such as npm or the official VS Code marketplace. Exposed hosts require removal of the injected SSH key and persistence artifacts; Cursor briefly took its service down during cleanup and urged users to update to 2.1.314 immediately.

Kevin Beaumont
@doublepulsar.com

New by me - Anthropic have been hacked to deliver remote access malware to millions of endpoints who use Claude Code. doublepulsar.com/anthropic-ha...

1292h ago
3 sources