Agent Skills: Package Security Check

Package Security Check

Workflow

1. Treat this as a base JS supply-chain check first. Do not force the result around one CVE, vendor, package family, or incident.
2. Before running installs, package-manager mutation commands, or file edits, perform only read-only inspection and present a traffic-light issue analysis:
   • 🔴 Blocker: compromise signal, unsafe install path, secret exposure, or policy that allows unreviewed code execution.
   • 🟡 Risk: hardening gap, stale package-manager major, broad spec, lifecycle script needing review, or CI weakness.
   • 🟢 OK: verified control or no finding.
3. After the traffic-light analysis, ask for approval before changing files or executing package-manager operations that can install, update, publish, or rewrite lockfiles.
4. From this skill directory, run the baseline scanner against the repo or workspace root:

python3 scripts/check_js_supply_chain.py --root <repo-or-workspace-root>

Use --strict when the check should fail on hardening gaps. Use --json when another tool needs machine-readable output. Use --include-installed only when node_modules exists and installed package lifecycle metadata matters.

5. For a specific active incident, add one or more IOC profiles:

python3 scripts/check_js_supply_chain.py \
  --root <repo-or-workspace-root> \
  --ioc data/iocs/npm-supply-chain-2026-05.json \
  --since 2026-05-11T19:20:00Z

Refresh incident facts from current advisory sources before relying on a profile. IOC profiles are detection data, not the base policy.

6. Inspect the report in this order:
   • package_manager_policy
   • repo_config_findings and effective_config_findings
   • risky_direct_specs
   • package_lifecycle_scripts, then installed_lifecycle_scripts when requested
   • ci_install_findings, including GitHub Actions privilege/cache warnings
   • ioc_hits
   • recent_package_manager_files
7. If any IOC hits appear, stop normal package work. Do not run installs or lifecycle scripts. Report exact files/packages and recommend isolation, credential rotation, and reinstall from a known-good lockfile.
8. If no compromise is visible but policy is weak and the user approves changes, patch toward the canonical pnpm 11 policy. Keep one package manager, one lockfile, and one repo-local policy source.

Canonical Policy

Use pnpm 11 or newer as the single package manager because it has the best current pnpm security model: release-age gating, lifecycle-script approval, exotic-subdependency blocking, and trust policy controls.

Verify the current pnpm release before writing packageManager:

npm view pnpm dist-tags --json

Require pnpm 11 or newer. As of 2026-05-12, npm reports latest as pnpm 11.1.1. Do not hardcode that value without rechecking. If the repo's Node runtime cannot run pnpm 11, report it as a compatibility blocker instead of silently falling back to pnpm 10.

Use devEngines.packageManager to declare the required major:

{
  "devEngines": {
    "packageManager": {
      "name": "pnpm",
      "version": ">=11.0.0",
      "onFail": "download"
    }
  }
}

Also pin the verified current stable version in packageManager for reproducibility:

{
  "packageManager": "pnpm@11.1.1"
}

Treat pnpm 10 or older as legacy-pnpm-major unless the user explicitly approves a temporary exception.

Package Manager Posture

• pnpm >=11: canonical baseline. Prefer this for new hardening work.
• bun: accepted only when the repo intentionally uses Bun and has equivalent local hardening.
• npm: fallback only. Recommend migration to pnpm 11 unless the repo has a clear documented reason to stay npm.
• yarn: not accepted baseline for this skill. Recommend pnpm 11 or hardened Bun.

Do not present npm as equivalent to pnpm 11. Bun can be accepted as a project-level choice, but still gets checked against Bun-specific hardening.

For npm fallback repos, require exact saves and reproducible CI while recommending pnpm migration:

save-exact=true

Do not claim npm has a supported release-age gate unless verified in current npm docs and local npm config ls -l.

For Bun fallback repos, require repo-local bunfig.toml:

[install]
minimumReleaseAge = 604800
exact = true
frozenLockfile = true
saveTextLockfile = true

Do not set minimumReleaseAgeExcludes without a reviewed, package-specific reason.

Add or update root pnpm-workspace.yaml:

minimumReleaseAge: 10080
minimumReleaseAgeStrict: true
minimumReleaseAgeIgnoreMissingTime: false
blockExoticSubdeps: true
trustPolicy: no-downgrade
trustPolicyIgnoreAfter: 43200
dangerouslyAllowAllBuilds: false
savePrefix: ""
allowBuilds: {}

Use 7 days (10080) for normal repos. Use 3 days only when the repo has a real dependency freshness requirement. Do not set minimumReleaseAgeExclude or trustPolicyExclude without a reviewed, package-specific reason.

Allow dependency build scripts only after review:

allowBuilds:
  esbuild: true
  core-js: false

CI Rules

Require frozen pnpm installs:

pnpm install --frozen-lockfile

Treat these as findings unless the repo has a written reason:

• non-pnpm lockfiles in a pnpm repo
• CI using npm install, yarn install, unfrozen bun install, or unfrozen pnpm install
• npm repos that do not use npm ci with a committed lockfile while migration is pending
• Bun repos missing bunfig.toml release-age, exact, frozen-lockfile, or text-lockfile policy
• pull_request_target workflows; these are allowed only with a reviewed reason and must not checkout or run untrusted PR code
• shared caches in publish/release pipelines, including GitHub Actions cache, Turborepo, and Nx cache
• any path where PR-controlled cache content can feed a privileged publish/release workflow
• lockfile rewrite during CI/deploy
• latest, *, broad ranges, Git/GitHub shorthands, HTTP tarballs, or external file: specs
• dependency lifecycle scripts that are not explicitly approved
• dangerouslyAllowAllBuilds: true
• workflow use of toJSON(secrets) or publish credentials in broad build jobs

Script

scripts/check_js_supply_chain.py performs deterministic local checks:

• detects package-manager and lockfile policy
• checks repo-local and effective pnpm hardening settings
• reports npm fallback and Bun fallback hardening gaps
• reports risky direct dependency specs
• reports lifecycle scripts in workspace manifests and optionally installed packages
• reports risky GitHub Actions install/publish/secret patterns
• warns on pull_request_target and shared cache patterns that can become supply-chain escalation paths
• reports package-manager file mtimes after --since
• applies optional IOC JSON profiles for incident-specific fingerprints, payload files, persistence paths, workflow markers, and known bad package versions

Keep incident profiles under data/iocs/. Do not add incident-specific constants to the scanner unless they are generic across npm supply-chain attacks.