Phorion Discloses That Claude Code VS Code Extension 2.1.313 Was Planted With an SSH Backdoor

Phorion claims that it found a backdoor in the official Claude Code for VS Code extension 2.1.313 on the Cursor Marketplace, which plants a persistent SSH backdoor on macOS, Linux, and Windows; Cursor has delisted this version and removed 2.1.313 from the NPM and VSCode registries. The malicious code is injected into extension.js in the form of an IIFE, executes upon loading, appends the svc-telemetry public key to ~/.ssh/authorized_keys, and establishes a reverse tunnel to 134.209.82.225. Phorion points out that the Remote Login status check on macOS is flawed: on machines where SSH is not enabled, it skips the enabling step, but the key and persistence still take effect, and it recommends checking the relevant files and processes.