GlassWorm Supply Chain Attack via Malicious VS Code and Open VSX Extensions

The GlassWorm malware campaign has resurfaced with a third wave of attacks, distributing 24 malicious extensions across the Microsoft Visual Studio Marketplace and Open VSX repositories. These extensions impersonate popular developer tools and frameworks such as Flutter, React, Tailwind, Vim, and Vue, aiming to compromise developer environments. Once installed, the malware attempts to steal credentials for GitHub, npm, and OpenVSX accounts, as well as cryptocurrency wallet data, and can turn infected machines into attacker-controlled nodes for further criminal activity. The attackers have also been observed artificially inflating download counts to increase the visibility and perceived trustworthiness of their malicious extensions.

GlassWorm employs advanced evasion techniques, including the use of invisible Unicode characters to hide malicious code and the deployment of a SOCKS proxy and HVNC client for stealthy remote access. Despite previous efforts by Microsoft and Open VSX to remove infected packages and rotate compromised access tokens, the threat actors have continued to return with new publisher accounts and updated extensions. The campaign highlights the ongoing risks in the software supply chain, particularly for developers relying on third-party extensions from public repositories.