Helpnetsecurity Malicious Claude Code Extension Distributes Persistent SSH Backdoor
Article Content
- •Compromised Claude Code extension version 2.1.313 distributed via Cursor Marketplace.
- •Malware installs a persistent SSH backdoor and collects sensitive user data.
- •Affected users should update to version 2.1.314 to mitigate risks.
A compromised version of Anthropic's Claude Code extension (version 2.1.313) was distributed through the Cursor Marketplace, attempting to install a persistent SSH backdoor on user systems. The malicious update was published under the legitimate publisher identity, affecting up to 5,000 users. The backdoor allows attackers to add an SSH key to the user's authorized_keys file, enabling remote access. It also collects sensitive information such as hostnames, usernames, and environment variables, sending this data to an attacker-controlled server. The malicious extension has been removed, and a clean version (2.1.314) has been released. The attack primarily targets macOS, Linux, and Windows systems, with specific persistence mechanisms for each platform. Cursor has temporarily shut down its marketplace to address the issue.
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