Merge PR #4931 from @romain-gaillard - Add additional GitHub audit detection rules

new: Github SSH Certificate Configuration Changed
new: Github Fork Private Repositories Setting Enabled/Cleared
new: Github Repository/Organization Transferred 

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Co-authored-by: nasbench <8741929+nasbench@users.noreply.github.com>

rules/cloud/github/github_ssh_certificate_config_changed.yml

@@ -0,0 +1,26 @@
+title: Github SSH Certificate Configuration Changed
+id: 2f575940-d85e-4ddc-af13-17dad6f1a0ef
+status: experimental
+description: Detects when changes are made to the SSH certificate configuration of the organization.
+references:
+    - https://docs.github.com/en/enterprise-cloud@latest/organizations/managing-git-access-to-your-organizations-repositories/about-ssh-certificate-authorities
+    - https://docs.github.com/en/enterprise-cloud@latest/admin/monitoring-activity-in-your-enterprise/reviewing-audit-logs-for-your-enterprise/audit-log-events-for-your-enterprise#ssh_certificate_authority
+author: Romain Gaillard (@romain-gaillard)
+date: 2024/07/29
+tags:
+    - attack.persistence
+    - attack.privilege_escalation
+    - 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:
+            - 'ssh_certificate_authority.create' # An SSH certificate authority for an organization or enterprise was created.
+            - 'ssh_certificate_requirement.disable' # The requirement for members to use SSH certificates to access an organization resources was disabled.
+    condition: selection
+falsepositives:
+    - Allowed administrative activities.
+level: medium