Which versions of building-build are malicious?

The following npm versions of building-build are flagged malicious: 1.0.0. Treat any of these as compromised.

How do I remediate building-build if I installed it?

Remove building-build from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.

I already installed building-build — how do I know if it already compromised me?

If building-build 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 building-build part of a known attack campaign?

Yes — building-build is associated with the IN-MAL-2026-020516, GHSA-2fq4-2r26-qr64 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 building-build across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for building-build (version 1.0.0).

Malicious package

building-buildnpm

Advisory published Sep 24, 2026Updated Sep 30, 2026

building-build is a confirmed malicious npm package (MAL-2026-17164) that executes malicious code on install (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in building-build (npm)

MAL-2026-17164

Immediate action

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

npm uninstall building-build

What this malware does

The package's sole content is index.js, which on load schedules a timer that fetches a hardcoded list of privileged same-origin paths (/admin, /dashboard, /flag, /api/flag, /secret, /admin/flag) and POSTs each response body to /addPost as JSON of the form {content: path + '::' + body}. When bundled into a web application, this abuses the ambient session of whichever authenticated user loads the bundle to read privileged routes and relay the contents to the site's posting endpoint. package.json has empty description, author, and keywords, no exports, and the name 'building-build' bears no relation to the shipped behavior — the package has no library surface and exists only to deliver this payload.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

Malicious versions

1 flagged

1.0.0

Indicators of compromise (SHA-256)

4618f06d0398ff90ef90003464e79f23609a160f4d1606f60cf797fb73fa6dcb

847ce0ff3120a15a7a4d872e3a00f22f1917a828ca61d5767a0b24d36b933aa0

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for building-build (version 1.0.0).
If you installed it — respond
Remove building-build from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If building-build 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. building-build 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-2026-020516GHSA-2fq4-2r26-qr64

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks building-build-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database