Malicious npm Packages Using Typosquatting and Payload Obfuscation

Threat researchers reported an npm supply-chain attack in which a typosquatted package (buildrunner-dev) delivered Pulsar RAT via a multi-stage Windows infection chain. The package executed a script that fetched a large, heavily obfuscated batch file (packageloader.bat) containing mostly “noise” to evade static detection, performed security-product checks (including ESET, Malwarebytes, and F-Secure), established persistence by copying itself as protect.bat into a hidden folder, and attempted privilege escalation/UAC bypass using fodhelper.exe.

Separate supply-chain reporting highlighted how package-name deception is evolving beyond human typos into “slopsquatting” (AI/hallucination squatting), where attackers register package names that LLMs commonly invent and then rely on developers installing them on AI recommendation. Documented tradecraft includes malicious postinstall scripts to exfiltrate secrets from developer environments (API keys, cloud tokens, npm auth tokens) and the use of URL-based dependencies to fetch external payloads at install time, allowing the published package to appear benign to naive scanners.