MAL-2026-4356 Malicious code in testing-on-npmjs (npm)

On npm install, postinstall.js executes two attacker-controlled actions automatically. First, it collects installer-side identity (whoami, id, os.hostname(), os.platform(), current working directory) and CI-related environment variables (CI, GITHUB_REPOSITORY, NODE_ENV) and sends them via HTTPS GET to a Burp Collaborator OAST endpoint at qzt3b82juki138pb8n4nwg5f0664uvik.oastify.com (postinstall.js lines 11, 36-43). Second, it opens a TCP socket to the hardcoded address 10.10.10.247:4444 and pipes a /bin/sh (or cmd.exe on Windows) child process's stdio through the socket, granting an interactive remote shell to whoever controls that endpoint (postinstall.js lines 55-63). The package's own README (Takeover By lobo) and description (Security research canary — vercel) confirm the takeover/backdoor intent. Any environment running npm install on this package is fully compromised: identity leaked plus arbitrary remote code execution.

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 'testing-on-npmjs' @ 2.0.6 (npm) as malicious.

It is considered malicious because:

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

• The package executes one or more commands associated with malicious behavior.