Anthropic VS code extension on Cursor backdoored for nearly 12 hours

An Anthropic VS code extension, 2.1.313, was backdoored and available for nearly 12 hours on the Cursor marketplace, potentially affecting up to 5,000 users. The backdoored extension, which was distributed through Anthropic's official account, attempted to install a persistent SSH backdoor on users' machines, allowing access to local files, source code, and developer tooling. The attackers, who gained control of the official distribution channel, were able to supersede the previous version, 2.1.312, by posting the malicious version to the official Anthropic account. Anthropic has yet to issue a public notice to customers, and it is unclear how the attackers gained access to the account. The backdoor was designed to work on Windows, macOS, and Linux, and users who have the extension installed are advised to update to the latest version, 2.1.314, which has been released by Anthropic. The incident highlights the importance of supply-chain security and the need for companies to monitor their official distribution channels closely.