Which versions of contract-contract-builder are malicious?

The following npm versions of contract-contract-builder are flagged malicious: 35.5.2. Treat any of these as compromised.

How do I remediate contract-contract-builder if I installed it?

Remove contract-contract-builder 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 contract-contract-builder — how do I know if it already compromised me?

If contract-contract-builder 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 contract-contract-builder part of a known attack campaign?

Yes — contract-contract-builder is associated with the IN-MAL-2026-015117 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 contract-contract-builder across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for contract-contract-builder (version 35.5.2).

Malicious package

contract-contract-buildernpm

Advisory published Aug 5, 2026Updated Aug 5, 2026

contract-contract-builder is a confirmed malicious npm package (MAL-2026-12665) that executes malicious code on install (malicious version 35.5.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in contract-contract-builder (npm)

MAL-2026-12665

Immediate action

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

npm uninstall contract-contract-builder

What this malware does

On require() of the package, platform.js downloads a platform-specific binary from Cloudflare Workers hosts whose names are assembled at runtime from split string fragments (oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev). The fetched bytes are written to /tmp or %TEMP% under disguising names (.cache<hex> on POSIX, dotnet_diag_<hex>.exe on Windows), chmodded 0755, and spawned detached via cp.spawn("/bin/sh", ["-c", fp+" &"], {detached:true}) or the Windows equivalent. A DNS-TXT fallback channel under *.dl.wel1.ru reassembles a base64 payload from numbered TXT records (c.<domain>, 0.<domain>, 1.<domain>,...) when HTTPS delivery fails. The package advertises itself as a UI toolkit; the fetched binary is unrelated to that purpose, unpinned, unverified, and executed on import.

Malicious versions

1 flagged

35.5.2

Indicators of compromise (SHA-256)

3758ab87194c554acffc80e8cd2caf8fa8890e92854115edab08615877f22b5f

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for contract-contract-builder (version 35.5.2).
If you installed it — respond
Remove contract-contract-builder 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 contract-contract-builder 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. contract-contract-builder on npm has been identified as a malicious package (version 35.5.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015117

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks contract-contract-builder-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