A large-scale software supply chain attack compromised over 400 npm packages through a self-propagating worm called ChainDrop, a new variant of Mini Shai-Hulud. The campaign exploits stolen npm publishing credentials to automatically modify and republish legitimate software releases. ChainDrop targets developer workstations and CI/CD environments, harvesting credentials from npm, GitHub, AWS, Kubernetes, and HashiCorp Vault before validating access and enumerating resources. The malware uses preinstall lifecycle scripts for automatic execution, establishes persistence through repository configuration modifications, and abuses GitHub Actions OIDC trusted publishing workflows. After stealing credentials, it autonomously propagates by downloading packages, inserting malicious payloads, and republishing them with incremented versions, demonstrating how compromised developer identities can enable widespread ecosystem compromise.