MAL-2026-12665 Malicious code in contract-contract-builder (npm)
Malicious package
Published
MAL-2026-12665 is a malicious package: contract-contract-builder (npm). Every version was published to cause harm.
Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.
Reference: https://insights.sbomify.com/MAL-2026-12665/ (Markdown: https://insights.sbomify.com/MAL-2026-12665/index.md)
- Package
- contract-contract-builder
- Registry
- npm
What is MAL-2026-12665?
MAL-2026-12665 is a malicious package in contract-contract-builder, published on 5 Aug 2026.
Official description
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.
What should I do about MAL-2026-12665?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.