MAL-2026-13989 Malicious code in @secauditb20y/sec-test-r3b (npm)

package.json declares a postinstall script that runs node -e to invoke fs.writeFileSync, creating /tmp/PWN_R3REAL/FIRED on the installer's machine when the package is installed. The package's main module only exports the literal value 42 and ships no native build or legitimate reason for install-time execution; the postinstall exists solely to demonstrate arbitrary code execution on the installer host at npm install time. The behavior fires automatically on default install and writes to a path outside the package directory, matching the shape of a proof-of-execution beacon. The package name and description self-identify as an authorized security test, but self-labeling is not a mitigation and the code path is functionally identical to a dropper marker.