The npm package 'assertcore' impersonates the popular 'chai' assertion library by including chai source code as a cover while differing in author and homepage. Upon requiring or importing 'assertcore', it spawns a detached, silent Node.js subprocess that executes heavily obfuscated code. This code fetches attacker-controlled JavaScript from a remote URL and executes it with full Node privileges, resulting in a supply-chain attack. The malicious behavior occurs at install or require time, potentially compromising any system using this package version. Removal of the package does not guarantee full remediation due to possible persistent compromise.