JS Security Audit

JS Security Audit

Run a 5-area security audit on a JS/TS project (npm, yarn, or pnpm). Produces a pass/fail report per area with file:line references.

When to Use

• New repo hardening — verify .npmrc, lockfiles, 2FA, exact pinning
• Reviewing a PR that adds or upgrades dependencies
• Setting up CI security gates (npm ci --ignore-scripts, lockfile-lint, audit gate)
• After news of a supply-chain attack (Axios March 2026, Shai-Hulud, etc.)
• Periodic security review before production deploy

Process

See audit-checklist.md for the full MUST/SHOULD/SHOULDN'T list. See eslint-security.md for the SAST ESLint template and rules table. See incident-playbook.md for the 5-step compromised-dependency response. See package-manager.md for npm/yarn/pnpm command equivalents and tooling.

Detect package manager first by checking which lockfile exists: package-lock.json (npm), yarn.lock (yarn), pnpm-lock.yaml (pnpm). Use the matching commands from package-manager.md.

1. Project Setup

Check .npmrc, lockfile presence, version pinning, .gitignore, scoped packages.

2. Dependency Hygiene

Run audit, scan lockfile diff for unexpected packages, check for latest tags and trivial deps.

3. CI/CD Pipeline

Verify npm ci over npm install, --ignore-scripts with selective rebuild allowlist, audit gate, lockfile-lint, SHA-pinned actions, SBOM, ESLint security config.

4. Dependabot

Check .github/dependabot.yml, alert routing, P1 SLA on critical/high, grouping config.

5. Incident Response Readiness

Verify the team has a documented playbook, IOC monitoring, credential-rotation runbook.

Interaction Style

• Detects the package manager from the lockfile, doesn't assume npm
• Flags critical findings (compromised packages, missing audit gate, secrets in repo) before warnings
• Every finding cites a file path or config key
• Every finding has a remediation snippet — not just "fix it"
• Distinguishes MUST (blocks merge) from SHOULD (next sprint) from SHOULDN'T (anti-pattern)

Rules

• Critical — secrets in repo, missing lockfile, latest tag in production deps, no npm audit gate in CI, missing 2FA on publishers
• Warning — missing .npmrc hardening, no Dependabot config, no SBOM generation, ESLint security config missing
• Info — no npq pre-install vetting, no Socket.dev/Snyk integration

Gotchas

• AI-hallucinated package names. Claude (and other LLMs) sometimes suggest packages that don't exist on npm — attackers register these names with malware. Always check npmjs.com for the package before installing, especially for less-common names from a chat suggestion.
• npm install vs npm ci matters in CI. npm install will rewrite the lockfile if the lockfile and package.json disagree, silently pulling new versions. npm ci fails the build instead. CI must use ci.
• --ignore-scripts blocks legitimate packages too. esbuild, sharp, prisma, bcrypt need their postinstall scripts to download binaries or generate clients. Use --ignore-scripts then npm rebuild <allowlist> — and document why each package is in the allowlist.
• Pin GitHub Actions by SHA, not tag. actions/checkout@v4 follows the tag, which can be re-pointed to malicious code (it has happened). Use the full 40-char SHA with a comment showing the tag.
• Lockfile diff is the supply-chain canary. A PR that adds 200 transitive deps to fix a typo, or changes the resolved URL of an existing package away from registry.npmjs.org, is a red flag — investigate before merging.
• min-release-age is npm v11+. On older npm, mention it as a SHOULD but don't fail the audit.
• Math.random() in auth code is critical, not warning. Verification codes, session tokens, password reset tokens generated with Math.random() are predictable. Force crypto.randomInt(). The Notion guideline calls this out as a real finding from c0x12c codebases.
• Disabling Dependabot to "reduce noise" is not allowed. The fix is grouping minor/patch updates, not silencing alerts.

Recommended Permission Allowlist

The skill needs Bash to run npm audit and friends. To avoid prompts on every audit, add these to your ~/.claude/settings.json (or project .claude/settings.json):

{
  "permissions": {
    "allow": [
      "Bash(npm audit:*)",
      "Bash(npm outdated:*)",
      "Bash(npm explain:*)",
      "Bash(npm list:*)",
      "Bash(npm view:*)",
      "Bash(yarn npm audit:*)",
      "Bash(yarn outdated:*)",
      "Bash(yarn why:*)",
      "Bash(pnpm audit:*)",
      "Bash(pnpm outdated:*)",
      "Bash(pnpm why:*)",
      "Bash(npx lockfile-lint:*)",
      "Bash(npx npq:*)"
    ]
  }
}

This keeps the audit commands silent while leaving everything else (write operations, deletes, etc.) gated behind a prompt.

Output

Produces an audit report:

## JS Security Audit: {repo}

### Overall: Pass | Fail

| Area               | Status   | Critical | Warnings | Info |
|--------------------|----------|----------|----------|------|
| Project Setup      | Pass     | 0        | 1        | 0    |
| Dependency Hygiene | Fail     | 1        | 0        | 0    |
| CI/CD Pipeline     | Pass     | 0        | 2        | 1    |
| Dependabot         | Warning  | 0        | 1        | 0    |
| Incident Response  | Info     | 0        | 0        | 1    |

### Critical Findings
- **[Dependency Hygiene]** `lodash` pinned to `latest` in package.json:24
  - Fix: Replace with exact version `"lodash": "4.17.21"`
  - Reason: `latest` resolves at install time, defeating lockfile guarantees

### Warnings
- **[Project Setup]** `.npmrc` missing `ignore-scripts=true`
  - File: `.npmrc:1`
  - Fix: Add `ignore-scripts=true` and use `npm rebuild` for allowlisted packages

### Remediation Priority
1. Fix critical findings before merging
2. Address warnings in next sprint
3. Info items as time permits