The GlassWorm malware has appeared on the Open VSX marketplace again, after a publisher’s account was compromised in a supply chain attack, Socket reports.
On January 30, a threat actor published malicious versions of four established VS Code extensions with over 22,000 combined downloads.
The extensions contained code that would execute at runtime, evade systems with Russian locales, resolve command-and-control (C&C) data from Solana transaction memos, and run additional code.
Consistent with previously observed activity, the extensions were repurposed to deploy a GlassWorm loader, but the fresh attack did not rely on typosquatting or cloned tools.
“By contrast, these four extensions were published under an established publisher account with a multi-extension history and meaningful adoption signals across ecosystems,” Socket notes.
The publisher also maintains Visual Studio Marketplace listings with thousands of downloads, but the analyzed incident only concerns Open VSX extensions.
“The threat actor published poisoned updates through an established publisher identity, and the Open VSX security team assessed the incident as consistent with leaked tokens or other unauthorized publishing access,” Socket notes.
macOS malware
The threat actor hid a nearly identical loader in the extension.js file of each extension. It loads code that profiles the system and receives instructions from a transaction memo on Solana.
The loader explicitly focuses on macOS systems, moving to the next stage only if OS checks are passed. The second payload is a Node.js JavaScript implant designed for data theft and persistence.
Once executed, the malware targets Firefox- and Chrome-based browsers to steal cookies, form history, login files, and wallet-extension artifacts. It also searches the system for Safari cookies, desktop cryptocurrency wallets, and macOS keychain, Apple Notes, and FortiClient VPN data.
Finally, it collects documents from the Desktop, Documents, and Downloads folders, and stages all the harvested information for exfiltration to hardcoded external destinations.
According to Socket, the malware specifically targets developer credentials and configuration, such as AWS and SSH information, increasing the risk of account compromise and lateral movement activities.
“This campaign shows a clear escalation in Open VSX supply chain abuse. The threat actor blends into normal developer workflows, hides execution behind encrypted, runtime-decrypted loaders, and uses Solana memos as a dynamic dead drop to rotate staging infrastructure without republishing extensions,” Socket notes.
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