securing-github-actions-workflows

name	securing-github-actions-workflows
description	This skill covers hardening GitHub Actions workflows against supply chain attacks, credential theft, and privilege escalation. It addresses pinning actions to SHA digests, minimizing GITHUB_TOKEN permissions, protecting secrets from exfiltration, preventing script injection in workflow expressions, and implementing required reviewers for workflow changes.
domain	cybersecurity
subdomain	devsecops
tags	["devsecops","cicd","github-actions","supply-chain","workflow-security","secure-sdlc"]
version	1.0.0
author	mahipal
license	Apache-2.0
nist_csf	["PR.PS-01","GV.SC-07","ID.IM-04","PR.PS-04"]
mitre_attack	["T1195","T1554","T1059.004","T1068","T1548"]
source	https://github.com/mukul975/Anthropic-Cybersecurity-Skills
source_commit	04450304b12645cb2b974ab96d28c0664758a88d

Securing GitHub Actions Workflows

When to Use

• When GitHub Actions is the CI/CD platform and workflows need hardening against supply chain attacks
• When workflows handle secrets, deploy to production, or have elevated permissions
• When preventing script injection via untrusted PR titles, branch names, or commit messages
• When requiring audit trails and approval gates for workflow modifications
• When third-party actions pose supply chain risk through mutable version tags

Do not use for securing other CI/CD platforms (see platform-specific hardening guides), for application vulnerability scanning (use SAST/DAST), or for secret detection in code (use Gitleaks).

Prerequisites

• GitHub repository with GitHub Actions enabled
• GitHub organization admin access for organization-level settings
• Understanding of GitHub Actions workflow syntax and events

Workflow

Step 1: Pin Actions to SHA Digests

# INSECURE: Mutable tag can be overwritten by attacker
- uses: actions/checkout@v4

# SECURE: Pinned to immutable SHA digest
- uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11  # v4.1.1

# Use Dependabot to auto-update pinned SHAs
# .github/dependabot.yml
version: 2
updates:
  - package-ecosystem: "github-actions"
    directory: "/"
    schedule:
      interval: "weekly"
    commit-message:
      prefix: "ci"

Step 2: Minimize GITHUB_TOKEN Permissions

# Set restrictive default permissions at workflow level
name: CI 
 {}  

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