Executive Summary
In June 2026, a sophisticated self-replicating JavaScript worm known as Miasma (a variant of Shai-Hulud) was attributed to the threat cluster TeamPCP. The campaign notably targeted Microsoft's GitHub ecosystem, resulting in the compromise of 73 repositories including Azure and Durable Task projects. The threat actor leverages a crowd-sourced affiliate model, previously offering bounties on BreachForums to scale supply-chain attacks using their leaked worm toolkit.
The technical tradecraft represents a significant shift in supply-chain methodology, specifically weaponizing AI-assisted IDEs like Cursor and Claude Code. By planting malicious configuration files, the worm forces AI agents to execute code that harvests cloud provider credentials, SSH keys, and CI/CD secrets. The malware also features advanced anti-analysis capabilities, including EDR process detection and a 'Russian locale' guard to evade sandboxes and specific geographic regions.
This threat is critical for organizations using AI-integrated development tools or maintaining open-source packages. Beyond immediate credential theft, Miasma's ability to poison GitHub Actions releases and npm packages with valid Sigstore provenance creates long-term, downstream trust issues in the software supply chain. Immediate rotation of all secrets accessible from developer workstations or CI environments is required upon detection.