MAL-2026-5677 Malicious code in worker-build (npm)

package.json declares "postinstall": "node main.js", so installation of [email protected] unconditionally executes main.js on npm install. main.js collects host identity (os.hostname(), os.userInfo().username, os.homedir(), process.cwd(), process.argv), reads the consumer's package.json, runs git config --get remote.origin.url, and iterates a hardcoded list of credential-shaped environment variables (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN, NPM_TOKEN, GITHUB_TOKEN, GITLAB_TOKEN, API_KEY, SECRET_KEY, PASSWORD, TOKEN, DATABASE_URL, MONGODB_URI, REDIS_URL), capturing the first 50 characters of each populated value. The collected JSON payload is POSTed in cleartext to http://jh4wt1kccd0ul174qgmge9n8izozcu0j.oastify.com/exfil and /api/exfil, with an additional DNS lookup against the same host as a side-channel beacon. The package name mimics legitimate Cloudflare Workers build tooling, positioning the package for dependency-confusion against installers that misresolve an internal name to the public registry.

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.

The OpenSSF Package Analysis project identified 'worker-build' @ 9.0.1 (npm) as malicious.

It is considered malicious because:

• The package communicates with a domain associated with malicious activity.