StepSecurity Details Compromise of codfish/semantic-release-action GitHub Action

Article Details

Attack Vectors

• The attacker force-pushed a malicious commit to codfish/semantic-release-action and redirected version tags to it, causing workflows using those mutable tags to run the payload.
• The modified composite action installs Bun and runs an obfuscated JavaScript payload with `if: always()` guards, including when earlier workflow steps fail.
• The payload searches public GitHub commit messages for operator instructions and a token, then uses GitHub APIs for command retrieval and secret exfiltration.
• The payload harvests GitHub tokens and other credentials, attempts to read secrets from the GitHub Actions runner's process memory, and commits malicious files to accessible repositories.
• The payload adds AI-assistant and editor startup hooks to repository files and local configurations, and attempts SSH propagation using hosts found in `~/.ssh/known_hosts` and `~/.ssh/config`.
• With registry credentials, the payload can publish secondary malicious packages to npm, PyPI, and RubyGems.

Defensive Notes

• Pin GitHub Actions to full-length commit SHAs rather than mutable version tags.
• Check and disable attacker-created repository rulesets that make compromised tags immutable before attempting recovery.
• Use compromised-action blocking and imposter-commit detection to prevent workflows from running compromised or tag-drifted action commits.
• Monitor runner process, file-access, and network activity; the article reports Harden-Runner detecting an attempted read of Runner.Worker process memory and terminating the process.
• Review repositories and developer-machine AI assistant and editor configurations for injected hooks and malicious files.