Another VS Code attack wave is in the spotlight, and security researchers are sounding the alarm. A malware family known as Glassworm has resurfaced across both the Microsoft Visual Studio Marketplace and the OpenVSX Registry, two widely used hubs for downloading VS Code extensions. For business owners who rely on development teams to keep operations running, this incident is an important reminder that even trusted, everyday software tools can be weaponized.

Deja Vu All Over Again

The Visual Studio Marketplace, owned by Microsoft, serves developers working in Visual Studio and Visual Studio Code. The OpenVSX Registry is the vendor-neutral alternative used by platforms like Gitpod, Eclipse Theia, SAP Business Application Studio, and other VS Code-compatible editors. Between the two, millions of developers rely on these extension libraries every day.

In September 2025, researchers discovered at least 24 fake extensions that were sneaking the Lumma Stealer onto Windows machines via tools that looked safe and legitimate. The VS Code attacks are a classic example of a supply chain attack. Instead of hacking one business directly, attackers compromise upstream tools that developers trust.

This was a direct cybersecurity threat to businesses with any development workflow, but the bad guys got caught, the extensions got deleted, and everyone thought it was over. The moment a developer downloads and installs one of these extensions, the malicious code activates quietly in the background.

However, Glassworm simply published new malicious extensions under different names.

How To Improve Software Development Security

Most of the malicious extensions pretend to be productivity boosters or theme packs. Red flags your team should watch for include:

• Fewer than 500 installs
• Created in the last 60 days
• Over-the-top promises
• Publisher name that looks randomly generated or copied from a legitimate company
• Permissions that ask for way more than they need (especially “Read and write all your files”)

Spotting the Glassworm malware is only part of the solution. You need to take action to address any malicious extensions that have already found their way in.

Audit and Freeze Extension Installations

While the immediate threat is being contained, freeze new extension installations and tell your developers to ask before installing anything new. Audit the installed extensions on every company machine, looking for anything added since September that’s not from a trusted source.

Require Marketplace Verification

Have teams stick with well-maintained, high-download extensions and avoid new or poorly documented ones. Turn on Microsoft’s built-in extension verification, which is off by default for many users.

Make Endpoint Security Non-Negotiable

Ensure every device in your organization has up-to-date endpoint protection with infostealer detection.

Build Supply Chain Awareness Into Policy

Treat third-party tools like any other risk surface. Create guidelines for code editor plugins, open-source packages, and other external components.

This VS Code attack isn’t some theoretical cybersecurity threat. Glassworm proved they can come back faster than the marketplaces can take them down. Until both Microsoft and Open VSX roll out stronger publisher verification, the safest move is to treat every unknown VS Code extension like a potential Trojan horse.

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