Imported from owasp/secure-agent-playbook (plugins/code-security-skills/skills/api-security-review/SKILL.md). Install upstream with npx skills add owasp/secure-agent-playbook --skill api-security-review. Copyright stays with the author (CC-BY-4.0).

API Security Review

Perform comprehensive API security assessment following plays/api-security-review.md.

Steps

1. Discovery & Reconnaissance

   • Parse OpenAPI/Swagger specs or scan code for endpoints
   • Identify authentication mechanisms (JWT, OAuth 2.0, API keys, mTLS)
   • Map API gateway and middleware configurations
   • Enumerate all API versions and deprecated endpoints

2. Authentication Deep Dive

   • JWT security (algorithm confusion, weak signing, token expiration)
   • OAuth 2.0 flows (PKCE, state parameter, redirect URI validation)
   • API key exposure and rotation policies
   • Session management and token storage

3. Assess All 10 OWASP API Risks with attack scenarios:

   • API1 BOLA — IDOR via predictable IDs, batch endpoint bypasses, ownership verification gaps
   • API2 Broken Authentication — JWT attacks, OAuth flaws, brute force, credential stuffing
   • API3 BOPA — Mass assignment, response over-exposure, field-level authz bypasses
   • API4 Resource Consumption — Rate limit bypasses, pagination abuse, GraphQL DoS
   • API5 BFLA — Admin endpoint discovery, horizontal/vertical privilege escalation
   • API6 Business Flows — Automated abuse, inventory exhaustion, scraping attacks
   • API7 SSRF — URL bypasses, DNS rebinding, cloud metadata access
   • API8 Misconfiguration — CORS bypasses, verbose errors, missing headers
   • API9 Inventory — Shadow APIs, zombie endpoints, version confusion
   • API10 Unsafe Consumption — XXE, deserialization, webhook replay attacks

4. Automated Testing

   • Run API security scanners (OWASP ZAP, Burp Suite, Postman tests)
   • Test for common vulnerabilities with specific payloads
   • Validate rate limiting and throttling mechanisms

5. API Gateway & Infrastructure Review

   • Kong, nginx, Envoy, AWS API Gateway configurations
   • WAF rules and bypass opportunities
   • TLS configuration and certificate validation

Output

Comprehensive API security report including:

• API surface inventory with authentication mechanisms
• Risk matrix with severity ratings for all 10 categories
• Detailed findings with proof-of-concept examples
• Exploit scenarios and business impact analysis
• Prioritized remediation roadmap with code examples
• Testing artifacts and vulnerability evidence

OWASP References

• OWASP API Security Top 10 (2023)
• OWASP ASVS v5.0 — V13: API and Web Service
• OWASP Testing Guide: WSTG-APIT
• OWASP Cheat Sheet: REST Security, GraphQL Security, JWT Security, OAuth 2.0