GitHub Workflow File Creation or Modification
The following analytic hunts for any creations or modifications to GitHub Actions workflow YAML files across the organization's Linux or Windows endpoints. This hunting query tracks all workflow file activity under…
Description
The following analytic hunts for any creations or modifications to GitHub Actions workflow YAML files across the organization's Linux or Windows endpoints. This hunting query tracks all workflow file activity under .github/workflows directories to help defenders establish baselines of legitimate CI/CD workflow creation patterns, identify unusual or unauthorized changes, and detect anomalies that may indicate supply chain compromise. GitHub Actions workflows execute with privileged access to secrets and deployment credentials, making them high-value targets for attackers. By monitoring workflow file modifications over time, defenders can identify suspicious patterns such as unexpected workflow creation on developer workstations, modifications outside normal change windows, or activity in repositories that don't typically contain workflows. This data is essential for detecting supply chain attacks like Shai-Hulud that inject malicious workflows across multiple repositories.
Detection logic
Detection requirements
- Platform
- ESXiLinuxmacOSSaaSWindows
The rule states no platform. This is derived from the 3 ATT&CK techniques it maps to.
- Log source category
- sysmon_eventid_11sysmon_for_linux_eventid_11
Known benign triggers
- Legitimate engineering activity regularly creates workflow YAMLs. Suppress by repository path allowlisting, CI hosts, change windows, or approval timeframes.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax | Only this detection cites it |
| github.com/SigmaHQ/sigma/pull/5658/files | 2 |
| securelist.com/shai-hulud-worm-infects-500-npm-packages-in-a-supply-chain-attack/117547/ | 3 |
| www.cisa.gov/news-events/alerts/2025/09/23/widespread-supply-chain-compromise-impacting-npm-ecosystem | 2 |
From the source
- At source
- Open at source
- Upstream identifier
- 2a9f3a2e-2c07-4c5f-9e42-8f8f0b6b6a12
- Tagged by the source as
- NPM Supply Chain CompromiseEndpointendpointSplunk CloudSplunk EnterpriseSplunk Enterprise Securityendpoint
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1