Sigma medium test sigma

Github Self-Hosted Runner Execution

Detects GitHub self-hosted runners executing workflows on local infrastructure that could be abused for persistence and code execution. Shai-Hulud is an npm supply chain worm targeting CI/CD environments. It installs runners on compromised systems to maintain access after credential theft, leveraging their access to secrets and internal networks.

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Detection Logic

{
  "selection_worker_img": [
    {
      "Image
| endswith": "\\Runner.Worker.exe"
    },
    {
      "OriginalFileName": "Runner.Worker.dll"
    }
  ],
  "selection_worker_cli": {
    "CommandLine
| contains": "spawnclient"
  },
  "selection_listener_img": [
    {
      "Image
| endswith": "\\Runner.Listener.exe"
    },
    {
      "OriginalFileName": "Runner.Listener.dll"
    }
  ],
  "selection_listener_cli": {
    "CommandLine
| contains": [
      "run",
      "configure"
    ]
  },
  "condition": "all of selection_worker_* or all of selection_listener_*"
}

False Positives

  • ⚠ Legitimate GitHub self-hosted runner installations on designated CI/CD infrastructure
  • ⚠ Authorized runner deployments by DevOps/Platform teams following change management
  • ⚠ Scheduled runner updates or reconfigurations on existing build agents
  • ⚠ Self-hosted runners that follow expected/known naming patterns
  • ⚠ Installation via expected/known configuration management tools (reflected mostly as parent process name)

Field Validations

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