Supply Chain Audit

"Trust, but verify -- and in software supply chains, verify everything twice." -- Tanya Janca, Alice and Bob Learn Application Security

Core Philosophy

Software supply chain security is not about avoiding dependencies -- it is about understanding the trust decisions you make with every install, add, or restore command. Every dependency is a delegation of trust: you are trusting that the package author writes secure code, that the registry has not been compromised, that no one has published a malicious version, and that the transitive dependencies you never chose are equally trustworthy.

The three pillars of supply chain audit:

1. Vulnerability Scanning -- Are any dependencies known to be vulnerable? Which CVEs apply? Are the vulnerable code paths reachable?
2. License Compliance -- Are the licenses compatible with the project's distribution model? Are there copyleft licenses that require source disclosure?
3. Maintenance Health -- Are dependencies actively maintained? Are security issues being addressed? Is the package at risk of abandonment?

The 10 domain principles, the knowledge-base lookup table and search protocol, the AI discipline rules, the anti-pattern catalog, and the error-recovery procedures live in references/vulnerability-sources.md under "Audit Methodology & Discipline."

Workflow

Phase 1: Vulnerability Scan

Objective: Identify all dependencies with known CVEs.

Run the ecosystem scanners (NuGet, npm, pip, yarn, pnpm), map each finding to CVSS severity, then adjust raw CVSS for contextual risk — reachability (is the vulnerable code path invoked?), exposure (internet-facing vs. internal vs. air-gapped), data sensitivity (PII, financial, credentials), exploitability (public exploit available?), and compensating controls (WAF, network segmentation). Never report raw CVSS as project risk.

Scanner commands + CVSS severity table + contextual-risk factors: references/vulnerability-sources.md.

Phase 2: License Compliance

Objective: Verify all dependency licenses are compatible with the project's distribution model.

Detect licenses, classify by category (permissive / weak copyleft / strong copyleft / proprietary / unknown), and flag genuine incompatibilities against the actual distribution model — a GPL-3.0 dependency may be acceptable in SaaS but a compliance failure in shipped desktop software.

License detection commands + classification matrix: references/license-matrix.md.

Phase 3: Maintenance Health

Objective: Assess the ongoing viability and security responsiveness of each dependency.

Evaluate health indicators (last release, open security issues, contributor count, repository status) and present them with evidence, not judgment — state the dates and counts, let the human draw the conclusion.

Health-indicator thresholds + check commands: references/vulnerability-sources.md.

State Block

<supply-chain-state>
mode: scan | license | health | report
project_path: [absolute path to project root]
ecosystems: [NuGet, npm, pip, etc.]
dependencies_scanned: [count]
cves_found: [count]
license_issues: [count]
health_concerns: [count]
last_action: [what was just completed]
next_action: [what should happen next]
</supply-chain-state>

Output Template

Full templates: references/vulnerability-sources.md | references/license-matrix.md | references/nuget-security-review.md

NuGet-Specific Review

For .NET projects, this skill produces management-ready reports combining update analysis with security findings. Use for "review NuGet packages", "audit .NET dependencies", preparing compliance/management reports, periodic security reviews, or onboarding to an existing .NET codebase.

Process: locate all .csproj files → dotnet list package --outdated (updates) → dotnet list package --vulnerable (security) → generate the two-part report: Part 1 Packages Requiring Updates (executive summary, update table, package-by-package business impact), Part 2 Security Vulnerabilities (executive summary, vulnerability table, plain-language risk), plus Recommendations categorized by urgency (immediate / scheduled / monitor).

Key references:

• Report template and review commands: references/nuget-security-review.md
• Severity classification and priority matrix: references/nuget-severity-guidelines.md
• Executive summary templates: references/nuget-executive-summary-templates.md
• Vulnerability databases and scanning tools: references/vulnerability-sources.md
• License compatibility matrix: references/license-matrix.md

Integration with Other Skills

• dependency-mapper -- use to understand structural implications of dependencies before auditing. Coupling metrics reveal which dependencies are most deeply embedded and hardest to replace.
• technical-debt-assessor -- outdated packages, license risks, and abandoned dependencies are quantifiable debt items with cost-to-fix and cost-to-carry.
• security-review-trainer -- supply chain vulnerabilities (OWASP A06:2021) from a code review perspective; this skill covers them from a dependency audit perspective.
• architecture-review -- dependency choices are architectural decisions that constrain the system's evolution.