- Two VSCode extensions exfiltrated sensitive user data to Chinese servers
- ChatGPT – 中文版 and ChatMoss had over 1.5 million installs combined
- Extensions used hidden iframes, commands, and SDKs to steal files and track activity
More than 1.5 million people may have had their sensitive data exfiltrated to Chinese hackers through two malicious extensions found on the VSCode Marketplace.
Security researchers at Koi Security said they discovered two malicious browser extensions in Microsoft’s Visual Studio Code (VSCode) Marketplace, the official Microsoft store for code editor add-ons.
The extensions were advertised as AI-based coding assistants. Indeed, they worked as advertised, providing users with a simple and convenient way to access a Generative Artificial Intelligence (GenAI) tool to help with coding. However, the tools were also uploading sensitive data to a third-party server in China without telling the users about it.
MaliciousCorgi
According to Koi, these are the add-ons in question, which are both still available for download on the marketplace :
ChatGPT – 中文版 (publisher: WhenSunset, 1.34 million installs)
ChatMoss (CodeMoss) (publisher: zhukunpeng, 150k installs)
Koi says both are part of the ‘MaliciousCorgi’ campaign, and both were sending the stolen data to the same server.
To exfiltrate the data, they used three distinct mechanisms, it was said. The first one is via real-time monitoring of files opened in VS Code client. As soon as the victim opens a file, its contents are encoded in Base64 and relayed to the servers.
“The moment you open any file – not interact with it, just open it – the extension reads its entire contents, encodes it as Base64, and sends it to a webview containing a hidden tracking iframe. Not 20 lines. The entire file,” the researchers explained.
The second mechanism is a server-controlled command that stealthily sends up to 50 files from the victim’s workspace, while the third one is a zero-pixel iframe in the extension’s webview where commercial analytics SDKs are loaded. These SDKs track user behavior, build identity profiles, and monitor other activity.
Microsoft told BleepingComputer it was looking into the situation, but the add-ons are still available for download.
Via BleepingComputer
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