Which versions of css-snap-target-polyfill are malicious?

The following npm versions of css-snap-target-polyfill are flagged malicious: 1.0.0. Treat any of these as compromised.

How do I remediate css-snap-target-polyfill if I installed it?

css-snap-target-polyfill establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

I already installed css-snap-target-polyfill — how do I know if it already compromised me?

If css-snap-target-polyfill was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Is css-snap-target-polyfill part of a known attack campaign?

Yes — css-snap-target-polyfill is associated with the IN-MAL-2026-020894 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find css-snap-target-polyfill across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for css-snap-target-polyfill (version 1.0.0).

Malicious package

css-snap-target-polyfillnpm

Advisory published Oct 4, 2026Updated Oct 4, 2026

css-snap-target-polyfill is a confirmed malicious npm package (MAL-2026-17487) that opens a backdoor for remote access (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in css-snap-target-polyfill (npm)

MAL-2026-17487

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall css-snap-target-polyfill

What this malware does

The package ships thunderboltRegistry.js, which uses child_process and process.platform to collect host information and POSTs it via fetch() to the hardcoded external endpoint http://dxpoc.gt.tc. The destination is unrelated to any CSS polyfill functionality the package name advertises, is served over cleartext HTTP, and is not caller-configurable. This behavior does not correspond to the declared purpose of a CSS snap-target polyfill, which has no legitimate need to execute shell commands or beacon host details to a third-party domain.

Malicious versions

1 flagged

1.0.0

Indicators of compromise (SHA-256)

00c104d427125b4acf88ecb83a58d563507b23bcb716cb87fbf7fc953d816d42

Detection & response playbook

Backdoor / remote access

Find it
Search your lockfiles and build artifacts for css-snap-target-polyfill (version 1.0.0).
If you installed it — respond
css-snap-target-polyfill establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If css-snap-target-polyfill was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Frequently asked questions

No. css-snap-target-polyfill on npm has been identified as a malicious package (version 1.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-020894

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks css-snap-target-polyfill-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring

Explore

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