MAL-2026-15995 Malicious code in multicore-kit (npm)

[email protected] is published under a spoofed author identity (Blake Embrey, maintainer of array-flatten) and advertises itself as an array utility, but multicore-kit.js contains a heavily obfuscated top-level IIFE that fires on require(). On import it creates ~/.vs_cache, writes an obfuscated JavaScript payload plus a synthesized package.json declaring axios, better-sqlite3, node-machine-id, and socket.io-client (with @primno/dpapi and sudo-prompt added on Windows), spawns npm install inside that staging directory, and then executes the decoded payload with node (or via powershell.exe on Windows). The Windows dependency set (@primno/dpapi to unwrap the Chrome/Edge Local State DPAPI key, better-sqlite3 to read the Login Data SQLite databases, socket.io-client for a C2 channel, node-machine-id for host fingerprinting, sudo-prompt for privilege escalation) is the standard toolkit of a browser-credential stealer and is unrelated to any array-flatten functionality. The main module uses obfuscator.io-style string-array rotation with a base64+URI decoder, and the on-disk payload embeds a second layer of the same obfuscation.

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.