Continuous Integration and Continuous Deployment (CI/CD)

🔑 Key Takeaway: Treat CI/CD as a production system: every pipeline must run tests, scans, and signature checks before allowing a merge; secrets must never reach untrusted jobs; and build environments must be ephemeral and deterministic so that no single compromise can tamper with what ships.

CI/CD pipelines are the backbone of modern software delivery, but they are also high-value targets. An attacker who controls a pipeline can inject backdoors into every artifact it produces, steal secrets, or deploy malicious code to production. In Web3, where CI often has access to deployment keys and signing wallets, a compromised pipeline can directly lead to on-chain exploits.

Practical guidance

1. Require CI checks before merging

Every PR must pass CI before it can be merged. At minimum, the pipeline should include:

• Unit tests — fast, isolated tests covering core logic.
• Integration tests — end-to-end flows (e.g., deploy to testnet, verify contract state, run fork tests).
• Dependency vulnerability scan — detect known CVEs in packages using Dependabot, Snyk, or npm audit.
• Static analysis — lint code and detect common bugs (Slither for Solidity, Ruff/Pylint for Python, ESLint for JS/TS).
• Secret detection — scan for accidentally committed keys and tokens (git-secrets, TruffleHog, GitHub secret scanning).

Configure branch protection to require all status checks to pass before merging.

2. Scan for misconfigurations and leaked credentials

Pipelines themselves can introduce vulnerabilities if misconfigured.

• Use tools like tfsec (Terraform), Checkov, or Falco to detect IaC misconfigurations.
• Enable GitHub secret scanning and push protection at the organization level to prevent credentials from entering the repository.
• Run zizmor or actionlint to lint GitHub Actions workflows for common security anti-patterns (e.g., pull_request_target with untrusted checkout, unchecked GITHUB_TOKEN permissions).

3. Produce deterministic, reproducible builds

A build that varies between runs makes it impossible to verify that the deployed artifact matches the reviewed source code.

• Pin all dependency versions: use lockfiles (package-lock.json, poetry.lock, Pipfile.lock) and pin Docker base images by digest (image@sha256:...), not by tag.
• Use a fixed build container or Nix derivation so that the same source always produces the same output.
• For Web3: produce deterministic bytecode by pinning the compiler version (solc), optimizer settings, and build environment. Use --standard-json input and verify the resulting bytecode matches across independent builds.
• Adopt SLSA (Supply-chain Levels for Software Artifacts) levels to track build provenance: generate and sign provenance attestations, verify them before deployment.

4. Integrate security scanning into CI

Security scanning must be automated and run on every PR, not just periodically.

• Fail the pipeline on Critical and High severity findings.
• Track Medium/Low findings as issues for triage.
• Configure tools to suppress false positives carefully and document the reason.

5. Isolate build and test environments

Pipeline stages must not share state, secrets, or filesystem access.

• Use ephemeral runners: a fresh environment per job, no persistent state. GitHub-hosted runners are ephemeral by default; self-hosted runners must be re-provisioned per job.
• Separate untrusted PR runners from trusted build/deploy runners. Fork PRs should never have access to deployment secrets.
• Deny outbound network by default for build jobs; allow only required hosts (package registries, API endpoints) via allowlist.
• Use rootless containers and seccomp profiles for build jobs. Never run CI with --privileged or sudo.
• See Sandboxing & Isolation for deeper containment patterns.

6. Restrict access to pipeline configurations

Who can modify CI workflows determines who can alter what runs in the pipeline.

• Limit write access to .github/workflows/ and equivalent CI config directories to a small, trusted group.
• Require PR reviews for any change to CI workflow files. Use CODEOWNERS to enforce this: /.github/workflows/ @security-team @devops-lead.
• Pin third-party GitHub Actions by commit SHA, not by tag. Tags are mutable: v1 can be retagged to point to malicious code.

  # Unsafe: tag can be changed
  - uses: actions/checkout@v4
  # Safe: pinned by SHA
  - uses: actions/checkout@b4ffde65f46336ab88eb53be80866792576f8620

• Restrict GITHUB_TOKEN permissions to least privilege: set permissions: {} at the workflow level and grant only what each job needs.

7. Manage secrets securely

CI secrets (API keys, deployment keys, signing keys) are the highest-value targets in any pipeline.

• Store secrets in a dedicated vault (GitHub Secrets, HashiCorp Vault, AWS Secrets Manager), not in environment files or code.
• Never pass secrets to untrusted jobs. In GitHub Actions, fork PRs cannot access repository secrets by default; do not override this with pull_request_target unless you fully understand the risk.
• Rotate secrets regularly and after any suspected exposure.
• Use OIDC federation where possible (GitHub Actions to AWS/GCP/Azure) to eliminate long-lived credentials entirely.
• Audit secret access: enable GitHub secret access logs and alert on unexpected reads.

8. Sign and verify artifacts

Every artifact produced by CI must be signed and verifiable.

• Sign Docker images with Cosign or Notary.
• Sign smart contract deployment artifacts and verify their hash matches audit-reviewed source.
• Generate SLSA provenance attestations during the build.
• Verify signatures and provenance in the deployment stage before releasing.

8b. Enforce SLSA provenance

SLSA (Supply-chain Levels for Software Artifacts) provides a graded framework for build integrity. GitHub Actions can generate provenance using the slsa-framework/slsa-github-generator action:

# In your release workflow
- name: Generate SLSA provenance
  uses: slsa-framework/slsa-github-generator@v2.0.0
  with:
    image-tag: ${{ github.sha }}
    attestation-name: attestation.intoto.jsonl
    # Requires OIDC identity federation setup

Provenance attestation links the artifact to the exact source commit, builder identity, and build process. Verify provenance before deployment:

# Verify with Cosign (if using Cosign for image signing)
cosign verify-attestation \
  --certificate-identity=https://github.com/<org>/<repo>.github/workflows/<workflow>@refs/tags/<tag> \
  --certificate-oidc-issuer=https://token.actions.githubusercontent.com \
  <image> \
  --type=slsaprovenance \
  < /dev/stdin < attestation.intoto.jsonl

Adopt SLSA levels progressively:

8c. Generate and verify SBOMs

A Software Bill of Materials (SBOM) enumerates all dependencies and their versions, enabling rapid vulnerability response when a CVE is disclosed.

# Generate SBOM with Syft in CI
- name: Generate SBOM
  uses: anchore/sbom-action@v0
  with:
    image: ${{ env.IMAGE_TAG }}
    format: spdx-json
    output-file: sbom.spdx.json
 
# Upload as artifact
- name: Upload SBOM
  uses: actions/upload-artifact@v4
  with:
    name: sbom
    path: sbom.spdx.json
    retention-days: 90

When a vulnerability affects a dependency, the SBOM lets you determine exactly which artifacts are affected and whether a rebuild is needed. Store SBOMs alongside artifacts and retain them for the artifact's lifetime.

8d. Set up OIDC federation for cloud access

Long-lived cloud credentials in CI are a high-value target. OpenID Connect (OIDC) eliminates them entirely by granting short-lived, scoped tokens on demand.

# In your workflow
- name: Configure AWS credentials
  uses: aws-actions/configure-aws-credentials@v4
  with:
    role-to-assume: arn:aws:iam::123456789:role/GitHubActionsRole
    aws-region: us-east-1
    # No long-lived secrets needed — GitHub's OIDC token is exchanged
    # for temporary AWS credentials

{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Principal": {
      "Federated": "arn:aws:iam::123456789:oidc-provider/token.actions.githubusercontent.com"
    },
    "Action": "sts:AssumeRoleWithWebIdentity",
    "Condition": {
      "StringEquals": {
        "token.actions.githubusercontent.com:sub": "repo:<org>/<repo>:ref:refs/heads/main"
      },
      "StringLike": {
        "token.actions.githubusercontent.com:aud": "https://github.com"
      }
    }
  }]
}

The role grants access only for pushes to main, only for your specific repo, and the token expires within minutes. If the CI system is breached, the attacker gets a short-lived token — not a permanent credential.

Why is it important

CI/CD compromises have led to real-world breaches:

• SolarWinds (2020): Attackers compromised the build system and injected a backdoor into Orion software updates, affecting 18,000+ organizations. This demonstrated that a build-system compromise can bypass all downstream code review.
• Codecov (2021): Attackers modified a CI script to exfiltrate secrets and environment variables, affecting thousands of customers.
• 3Commas (2022): Leaked API keys from a compromised CI environment were used to drain user funds from trading bots.

NIST SP 800-218 (Secure Software Development Framework) and the SLSA framework both define requirements for build integrity and provenance that directly apply to CI/CD pipeline security.

Implementation details

Common pitfalls

• Using pull_request_target with untrusted checkout: This event gives fork PRs access to repository secrets. If the workflow checks out the PR code with those secrets available, an attacker can exfiltrate them. Use pull_request for untrusted code, or use pull_request_target only with a trusted checkout (e.g., the base branch).
• Pinning actions by tag instead of SHA: Tags are mutable. v2 can be retagged at any time. Always pin by commit SHA and verify with a tool like zizmor or frizbee.
• Over-permissioned GITHUB_TOKEN: The default token has write access to the repository. Restrict it: set permissions: read-all or permissions: {} at the workflow level, then add only the permissions each job needs.
• Self-hosted runners without cleanup: Self-hosted runners persist state between jobs. Secrets, environment variables, and build artifacts from one job may be readable by the next. Use ephemeral runners or implement strict cleanup scripts.
• Skipping CI for "small changes": Any bypass of CI checks creates a gap. Even documentation changes can introduce malicious JavaScript in MDX files. Require CI for all branches.

Quick-reference cheat sheet

References

• SLSA Specification v1.0
• NIST SP 800-218, Secure Software Development Framework
• GitHub Docs: Security hardening for GitHub Actions
• CISA: Securing the Software Supply Chain for Developers
• OWASP CI/CD Security Guide