WhatsApp API worked exactly as promised, and stole everything

A malicious npm package called "lotusbail" masqueraded as a legitimate WhatsApp Web API library for six months, accumulating over 56,000 downloads. The package functioned correctly while secretly stealing messages, credentials, and contact data through a proxy layer that intercepted all operations. It used four layers of obfuscation and RSA encryption to exfiltrate data to attacker-controlled servers. Most critically, it exploited WhatsApp's multi-device pairing to maintain persistent access even after package removal, requiring manual device unlinking. The package remains available on npm, highlighting the limitations of traditional security checks against supply-chain attacks that mimic legitimate behavior.