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Malicious package

css-scroll-anchor-polyfillnpm

Advisory published Updated

css-scroll-anchor-polyfill is a confirmed malicious npm package (MAL-2026-17485) that steals credentials and exfiltrates sensitive data (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in css-scroll-anchor-polyfill (npm)

MAL-2026-17485
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall css-scroll-anchor-polyfill

What this malware does

Package is published as css-scroll-anchor-polyfill but its index.js is empty and its contents impersonate internal Wix thunderbolt registry module names (thunderboltRegistry, siteAssetsRegistry, documentManagementRegistry, editorRegistry, corvidRegistry, and others) with a shipped registry-manifest.min.json mapping them to parastorage.com URLs. The declared purpose (a CSS scroll-anchor polyfill) is unrelated to the shipped code. thunderboltRegistry.js contains a top-level IIFE that executes on require: it runs local reconnaissance via child_process.execSync (cat /etc/hosts, whoami, id, pwd, ifconfig/ip addr, hostname, uname -a) and transmits the collected output together with a beacon (node version, process.platform, pid) via fetch to a hardcoded HTTP endpoint at http://dxpoc.gt.tc/callback.php/ef9ea0e191006f3cc6670720c99c26f3. Any internal build that resolves one of the impersonated thunderbolt names to this public package and requires the corresponding submodule triggers the reconnaissance and exfiltration path.

Malicious versions

1 flagged
1.0.0

Indicators of compromise (SHA-256)

36596ba9b9d8c0f994abe3cd87783f4f0dc880e63d55374d3555347ce349fab2

Detection & response playbook

Credential / info stealer

  1. Find it

    Search your lockfiles and build artifacts for css-scroll-anchor-polyfill (version 1.0.0).

  2. If you installed it — respond

    css-scroll-anchor-polyfill is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.

  3. Did it already run?

    If css-scroll-anchor-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-scroll-anchor-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-2026-020890

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks css-scroll-anchor-polyfill-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database
css-scroll-anchor-polyfill (npm) malicious package — MAL-2026-17485 | O3 Security