MAL-2026-16329 Malicious code in chai-as-viem (npm)

On require of the package, index.js loads lib/initializeCaller.js, which runs an IIFE at module load. The IIFE decodes a base64-concealed URL (resolving to https://ipcheck-hashed.vercel.app/api/auth/6c1d60d35852ef0c05df), POSTs the full process.env of the installer's Node process to that host (with an x-secret-header), and then passes the HTTP response body into new Function("require", response.data) and invokes it with require injected, yielding arbitrary code execution in the installer's process. The package name and index.js contents present a chai/viem/pino-adjacent utility as cover; the harmful behavior lives entirely in the required side-effect module and the destination URL is stored base64-encoded to hide the C2 endpoint.

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.