MAL-2026-12665

    Dashboard / Malicious Package / MAL-2026-12665

    MAL-2026-12665

    Published: 5 Aug 2026Last Modified: 5 Aug 2026

    Summary: Malicious code in contract-contract-builder (npm)

    Details: Source: amazon-inspector (3758ab87194c554acffc80e8cd2caf8fa8890e92854115edab08615877f22b5f) 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.

    References: https://www.npmjs.com/package/contract-contract-builder/v/35.5.2

    Affected packages

    Package

    Name: contract-contract-builder

    Purl: pkg:npm/contract-contract-builder

    Affected ranges

    Type: N/A

    Events:

    Introduced- None
    Fixed -None

    Affected versions

    35.5.2