Skype, Slack, Other Electron-Based Apps Can Be Easily Backdoored

An anonymous reader quotes a report from Ars Technica: The Electron development platform is a key part of many applications, thanks to its cross-platform capabilities. Based on JavaScript and Node.js, Electron has been used to create client applications for Internet communications tools (including Skype, WhatsApp, and Slack) and even Microsoft’s Visual Studio Code development tool. But Electron can also pose a significant security risk because of how easily Electron-based applications can be modified without triggering warnings. At the BSides LV security conference on Tuesday, Pavel Tsakalidis demonstrated a tool he created called BEEMKA, a Python-based tool that allows someone to unpack Electron ASAR archive files and inject new code into Electron’s JavaScript libraries and built-in Chrome browser extensions. The vulnerability is not part of the applications themselves but of the underlying Electron framework — and that vulnerability allows malicious activities to be hidden within processes that appear to be benign. Tsakalidis said that he had contacted Electron about the vulnerability but that he had gotten no response — and the vulnerability remains.

While making these changes required administrator access on Linux and MacOS, it only requires local access on Windows. Those modifications can create new event-based “features” that can access the file system, activate a Web cam, and exfiltrate information from systems using the functionality of trusted applications — including user credentials and sensitive data. In his demonstration, Tsakalidis showed a backdoored version of Microsoft Visual Studio Code that sent the contents of every code tab opened to a remote website. The problem lies in the fact that Electron ASAR files themselves are not encrypted or signed, allowing them to be modified without changing the signature of the affected applications. A request from developers to be able to encrypt ASAR files was closed by the Electron team without action.