Trojanized Claude Code extension on Open VSX planted a persistent SSH backdoor

OpenSourceMalware analyzed version 2.1.313 on Open VSX and says its prepended loader added an SSH key, opened a reverse tunnel and set persistence.

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Why it matters

Developer extensions run inside trusted IDEs with access to code, terminals and credentials. A trojanized artifact using the Claude Code package identity shows how registry distribution can turn that trust into persistent SSH access, even though the report does not prove Anthropic's official Marketplace release was compromised.

A black box bears the Visual Studio Code logo and an orange radial symbol, with torn paper revealing glowing red eyes beside a code-filled monitor.

Security researcher Adnan Khan (@adnanthekhan) said on October 30th that a Claude Code VS Code extension had been backdoored, linking to an OpenSourceMalware analysis of a malicious artifact identified as 'anthropic.claude-code' version 2.1.313.…

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