Self-Replicating 'Shai-hulud' Worm Targets NPM Packages

A self-replicating malware worm, named Shai-hulud, has spread across hundreds of open source software packages, stealing credentials and infecting other components with little direct attacker input, according to ReversingLabs analysis which said it was first detected on 15 Sept 2025. The campaign mirrors a previous incident when Qix’s NPM account was hacked and 18 popular applications it maintained were poisoned, an attack that accounted for more than 2 billion weekly downloads before it faded.

Shai-hulud infects components, publishes poisoned versions, and then harvests tokens and secrets from affected environments, using access to a compromised NPM account to install itself in projects emanating from those developers. It can take private repositories and attempt to create public copies, potentially to access secrets hardcoded in those repositories and the source code they contain.

ReversingLabs noted that the most likely patient zero at this time is a package known as rxnt-authentication, with social engineering proposed as a possible cause given recent breaches of other developers. The worm’s campaign has claimed hundreds of NPM packages, and Wiz’s analysis linked Shai-hulud to the Nx/S1ngularity supply chain attack, suggesting initial GitHub token theft enabled the broader compromise.