Github Self Hosted Runner Changes Detected

A self-hosted runner is a system that you deploy and manage to execute jobs from GitHub Actions on GitHub.com. This rule detects changes to self-hosted runners configurations in the environment. The self-hosted runner configuration changes once detected, it should be validated from GitHub UI because the log entry may not provide full context.

title: Github Self Hosted Runner Changes Detected
id: f8ed0e8f-7438-4b79-85eb-f358ef2fbebd
status: test
description: |
    A self-hosted runner is a system that you deploy and manage to execute jobs from GitHub Actions on GitHub.com.
    This rule detects changes to self-hosted runners configurations in the environment. The self-hosted runner configuration changes once detected,
    it should be validated from GitHub UI because the log entry may not provide full context.
author: Muhammad Faisal (@faisalusuf)
date: 2023-01-27
references:
    - https://docs.github.com/en/actions/hosting-your-own-runners/about-self-hosted-runners#about-self-hosted-runners
    - https://docs.github.com/en/organizations/keeping-your-organization-secure/managing-security-settings-for-your-organization/reviewing-the-audit-log-for-your-organization#search-based-on-operation
tags:
    - attack.impact
    - attack.discovery
    - attack.collection
    - attack.persistence
    - attack.privilege-escalation
    - attack.initial-access
    - attack.stealth
    - attack.t1526
    - attack.t1213.003
    - attack.t1078.004
logsource:
    product: github
    service: audit
    definition: 'Requirements: The audit log streaming feature must be enabled to be able to receive such logs. You can enable following the documentation here: https://docs.github.com/en/enterprise-cloud@latest/admin/monitoring-activity-in-your-enterprise/reviewing-audit-logs-for-your-enterprise/streaming-the-audit-log-for-your-enterprise#setting-up-audit-log-streaming'
detection:
    selection:
        action:
            - 'org.remove_self_hosted_runner'
            - 'org.runner_group_created'
            - 'org.runner_group_removed'
            - 'org.runner_group_runner_removed'
            - 'org.runner_group_runners_added'
            - 'org.runner_group_runners_updated'
            - 'org.runner_group_updated'
            - 'repo.register_self_hosted_runner'
            - 'repo.remove_self_hosted_runner'
    condition: selection
falsepositives:
    - Allowed self-hosted runners changes in the environment.
    - A self-hosted runner is automatically removed from GitHub if it has not connected to GitHub Actions for more than 14 days.
    - An ephemeral self-hosted runner is automatically removed from GitHub if it has not connected to GitHub Actions for more than 1 day.
level: low

• T1078.004Cloud Accounts
• T1213.003Code Repositories
• T1526Cloud Service Discovery

• https://docs.github.com/en/actions/hosting-your-own-runners/about-self-hosted-runners#about-self-hosted-runners↗
• https://docs.github.com/en/organizations/keeping-your-organization-secure/managing-security-settings-for-your-organization/reviewing-the-audit-log-for-your-organization#search-based-on-operation↗