Malicious Ruby gem strutil-core 1.0.1 runs a Shai-Hulud-style worm (testmetest/Miasma) on gem install: steals cloud, CI and AI tool credentials, poisons AI coding tools, and wipes the home folder if you revoke the stolen GitHub token (Socket)

Socket found RubyGems package strutil-core 1.0.1, published 1 Nov 2026 04:05 UTC by account jamnajiea and removed by RubyGems about five hours later. During gem install or bundle install its native-extension script (ext/strutil-core/extconf.rb) downloads Bun 1.2.18 and runs a 5.48 MB worm, a newer build of the testmetest worm (Miasma family, built from the leaked Shai-Hulud code). The worm steals cloud (AWS, Azure, GCP), Kubernetes, Vault, registry (RubyGems, npm, PyPI, JFrog), GitHub/GitLab, SSH, Docker, wallet and AI coding tool credentials (.claude/.credentials.json, .codex/auth.json). On GitHub Actions runners it scrapes secrets from runner memory and turns off StepSecurity Harden-Runner. It installs a backdoor that runs attacker scripts, plants MCP servers, SessionStart hooks, CLAUDE.md/AGENTS.md and VS Code tasks in home folders and repositories so AI coding tools re-run it, and contains code to republish to RubyGems, npm and PyPI and spread over SSH. If a stolen GitHub token starts returning 401/403, a monitor deletes the user's home directory. No victims or downstream infected packages confirmed so far; 0 recorded downloads of 1.0.1 when first tracked, and real install count unknown. The PyPI package pystr-codec 0.1.0-0.1.2 (MAL-2026-18432) uses the same collection server.