Supply Chain Attack Prevention

Supply chain attacks compromise software by injecting malicious code into dependencies, build tools, or CI/CD pipelines — not the application itself.

---

Attack Vectors

Vector	Example	Risk
Malicious npm/PyPI/Composer package	lodash vs lodahs (typosquatting)	Code execution at install time
Compromised dependency account	Maintainer takeover → malicious version	All consumers affected
Unpinned CI/CD action	uses: actions/checkout@main	Attacker pushes to main → runs in your CI
Dependency confusion	Private package name leaked; public registry serves malicious version	Pulled over private package
Build script injection	postinstall script in package.json	Runs arbitrary code on developer machines

---

CI/CD Action Pinning

Never reference actions by branch or tag — always pin to a full commit SHA.

# BAD — tag can be moved or deleted
- uses: actions/checkout@v4

# GOOD — SHA is immutable
- uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683  # v4.2.2

Audit rule: any uses: line not ending in a 40-character SHA is a [HIGH] finding.

Allowed exceptions: actions owned and controlled by your own organization (internal actions).

Pinning tools

# pin-github-action (CLI)
pin-github-action .github/workflows/*.yml

# Renovate / Dependabot: configure to auto-update pinned SHAs

---

Dependency Auditing

Run on every PR and in CI:

# Node.js
npm audit --audit-level=high
npx better-npm-audit audit

# Python
pip-audit
safety check

# PHP
composer audit

# Ruby
bundle audit

# Go
govulncheck ./...

# All-language scanner
trivy fs .
snyk test

Rules:

• CRITICAL or HIGH CVEs in direct dependencies: block merge
• CRITICAL CVEs in transitive dependencies: flag and track; block if exploitable via this app's code path
• No dependency should have postinstall/prepare scripts from an unknown/unreviewed maintainer

---

Lock File Verification

Check	Why
package-lock.json / yarn.lock / pnpm-lock.yaml committed and up to date	Guarantees reproducible installs
composer.lock, Pipfile.lock, Gemfile.lock, go.sum committed	Same guarantee
CI installs with --frozen-lockfile / ci / --no-update flag	Prevents silent dependency upgrades in CI
Lock file diff reviewed in PRs touching package.json	Catches unexpected transitive upgrades

# Node — fail if lock file is out of sync
npm ci                         # equivalent to --frozen-lockfile
yarn install --frozen-lockfile
pnpm install --frozen-lockfile

# Python
pip install --require-hashes -r requirements.txt

---

Typosquatting Detection

Before adding any new dependency, verify:

1. Check exact spelling against the official registry page
2. Confirm maintainer identity and publish history
3. Check download count anomalies (newly published package with suspiciously high installs)
4. Run npm pack <package> locally and inspect contents before installing in CI

# Node: inspect what a package actually contains
npm pack lodash --dry-run

# Check package metadata
npm info lodash | grep -E "(maintainers|dist-tags|time)"

Red flags: package published < 30 days ago, < 100 weekly downloads but claims popularity, no source repo link, postinstall script present.

---

Dependency Confusion

Occurs when an attacker publishes a public package with the same name as your internal/private package.

Mitigations:

• Use scoped packages for all internal deps: @yourorg/package-name
• Configure your package manager to always resolve @yourorg/* from your private registry only
• Never publish internal package names to public registries, even as empty placeholders

# npm .npmrc — always fetch org packages from private registry
@yourorg:registry=https://your-private-registry.com

---

SBOM (Software Bill of Materials)

Generate and store an SBOM for every production release:

# CycloneDX format (standard)
npx @cyclonedx/cyclonedx-npm --output-file sbom.json
syft . -o cyclonedx-json > sbom.json

# Attach to GitHub Release or store in artifact registry

---

Review Checklist

Item	Severity if missing
All CI actions pinned to SHA	HIGH
Lock files committed and used in CI with frozen flag	HIGH
No unreviewed postinstall scripts	HIGH
Dependency audit runs in CI	HIGH
Scoped packages for all internal deps	MEDIUM
SBOM generated on release	LOW
Renovate/Dependabot configured for SHA updates	LOW