Grafana GitHub Breach: Stolen Token Led to Codebase Theft

Overview

Grafana Labs disclosed a security incident involving unauthorized access to its GitHub environment. A stolen GitHub access token allowed attackers to download private source code repositories. This event highlights the critical importance of securing developer credentials and monitoring access to source control systems.

Technical Analysis

• Attackers gained unauthorized access to Grafana’s GitHub environment using a previously stolen GitHub access token. The specific method by which the token was initially compromised is not publicly detailed.
• The stolen token provided sufficient permissions for the attackers to access and download private source code repositories.
• Upon detection, Grafana Labs immediately revoked the compromised token.
• The incident did not impact Grafana’s production environment, customer data, or hosted Grafana Cloud instances.

Detection

• Monitor GitHub audit logs for unusual repo.download or repo.clone events, especially from unknown IP addresses, user agents, or by tokens with broad permissions.
• Look for large data egress from source code management platforms that deviate from normal developer activity.
• Implement alerts for access token usage from unexpected geographical locations or outside of typical working hours.
• Review GitHub organization audit logs for oauth_application.access_token_created or oauth_application.access_token_deleted events that are not tied to known administrative actions.

Mitigations

1. Rotate GitHub Access Tokens: Regularly rotate all personal access tokens (PATs) and OAuth tokens, especially those with broad repository access.
2. Enforce Multi-Factor Authentication (MFA): Mandate MFA for all GitHub accounts, including service accounts, to prevent unauthorized access even if credentials are stolen.
3. Implement Least Privilege: Grant GitHub tokens and user accounts only the minimum necessary permissions required for their function. Avoid broad repo scopes.
4. Monitor GitHub Audit Logs: Implement continuous monitoring and alerting for suspicious activities such as unusual repository cloning, large data downloads, or token creation/deletion.
5. Review Connected OAuth Apps: Regularly audit and revoke access for any OAuth applications connected to GitHub accounts that are no longer needed or appear suspicious.

References

• https://www.bleepingcomputer.com/news/security/grafana-says-stolen-github-token-let-hackers-steal-codebase/

Indicators of Compromise

No public IOCs available at time of writing.

Detection Rules (Sigma)

GitHub Unusual Repository Download

title: GitHub Unusual Repository Download
id: 921c1f71-a2c6-4d0f-a82f-2d7c5e4f1a3b
status: experimental
description: Detects suspicious repository download or clone activity in GitHub audit logs, potentially indicating unauthorized access or data exfiltration.
logsource:
  product: github
  service: audit
detection:
  selection_action:
    action|contains: ['repo.download', 'repo.clone']
  condition: selection_action
level: high

MITRE ATT&CK

• T1078.003 — Local Accounts
• T1020 — Automated Exfiltration