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

OpenSourceMalware's analysis of a trojanized 'anthropic.claude-code' extension version 2.1.313 on the Open VSX registry found a prepended loader that added an SSH key, opened a reverse tunnel and set persistence, security researcher Adnan Khan (@adnanthekhan) said on October 30th. The report does not prove Anthropic's official Marketplace release was compromised, but it shows how registry distribution can turn IDE extension trust into persistent SSH access to code, terminals and credentials.

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. By Ryan Merket https://runtimewire.com/author/ryan-merket · Published Primary source: x.com https://x.com/adnanthekhan/status/2116010483702706337 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. Security researcher Adnan Khan @adnanthekhan https://x.com/adnanthekhan said on October 30th that a Claude Code VS Code extension had been backdoored, linking to an OpenSourceMalware analysis https://opensourcemalware.com/blog/trojanized-claude-code-extension-plants-persistent-ssh-backdoor of a malicious artifact identified as 'anthropic.claude-code' version 2.1.313.… When you purchase through links in our articles, we may earn a small commission https://runtimewire.com/affiliate-monetization-standards . This doesn’t affect our editorial independence.