Vulnerability MAL-2026-19054

strutil-core 1.0.1, presented as "Core string utilities for Ruby", runs its payload at install time from its native-extension step. The step downloads the Bun JavaScript runtime from Bun's GitHub releases into a hidden temporary directory (/tmp/.b_/) and runs ext/strutil-core/index.js from the installed gem. Observed in a sandboxed gem install strutil-core -v 1.0.1: the script read 51 credential stores belonging to other tools (cloud: AWS, Azure, Google Cloud, Vault; forges: GitHub CLI, GitLab CLI, git credentials, SSH keys; package registries: npm, PyPI, RubyGems, NuGet, Composer, Yarn; Docker and Kubernetes; Claude Code and Codex logins; database client files; cryptocurrency wallets; Terraform, Databricks, Hugging Face, Vercel and Kaggle tokens). It then used them against AWS STS, Secrets Manager and Systems Manager Parameter Store in 18 regions and ECR in 11, Azure Resource Manager and Microsoft Graph, Google Cloud's metadata service and Resource Manager, and the GitHub, GitLab and GitHub Container Registry APIs, and connected to paleasbest.top. It installed persistence as a systemd user service (~/.config/systemd/user/pkg-runtime.service) with ~/.local/share/runtimes/sync.py and a copy of the JavaScript at /.config/index.js, and rewrote the Cursor editor's MCP configuration (/.cursor/mcp.json). paleasbest.top is the server of the pystr-codec PyPI worm (MAL-2026-18432, Miasma family); this appears to be the same worm repackaged as a gem.