Github Outside Collaborator Detected

Detects when an organization member or an outside collaborator is added to or removed from a project board or has their permission level changed or when an owner removes an outside collaborator from an organization or when two-factor authentication is required in an organization and an outside collaborator does not use 2FA or disables 2FA.

Sigma rule (View on GitHub)

 1title: Github Outside Collaborator Detected
 2id: eaa9ac35-1730-441f-9587-25767bde99d7
 3status: test
 4description: |
 5        Detects when an organization member or an outside collaborator is added to or removed from a project board or has their permission level changed or when an owner removes an outside collaborator from an organization or when two-factor authentication is required in an organization and an outside collaborator does not use 2FA or disables 2FA.
 6author: Muhammad Faisal
 7date: 2023/01/20
 8references:
 9    - https://docs.github.com/en/organizations/keeping-your-organization-secure/managing-security-settings-for-your-organization/reviewing-the-audit-log-for-your-organization#audit-log-actions
10    - https://docs.github.com/en/organizations/keeping-your-organization-secure/managing-two-factor-authentication-for-your-organization/requiring-two-factor-authentication-in-your-organization
11tags:
12    - attack.persistence
13    - attack.collection
14    - attack.t1098.001
15    - attack.t1098.003
16    - attack.t1213.003
17logsource:
18    product: github
19    service: audit
20    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'
21detection:
22    selection:
23        action:
24            - 'project.update_user_permission'
25            - 'org.remove_outside_collaborator'
26    condition: selection
27fields:
28    - 'action'
29    - 'actor'
30    - 'org'
31    - 'actor_location.country_code'
32falsepositives:
33    - Validate the actor if permitted to access the repo.
34    - Validate the Multifactor Authentication changes.
35level: medium

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