📚 Complete API Security Testing Guide

API Security Testing —
Methods, Tools & Best Practices

Learn API security testing methods and scan your API with a free online scanner.

API Security Testing Methods

🔬

Dynamic Application Security Testing (DAST)

DAST tests APIs from the outside by sending crafted requests and analyzing responses. It requires no access to source code and simulates real-world attacks. SEC Scanner uses DAST techniques to identify vulnerabilities in running APIs.

📝

Static Application Security Testing (SAST)

SAST analyzes API source code for security flaws before deployment. While powerful for catching code-level issues, it doesn't detect runtime vulnerabilities or configuration problems. Best used alongside DAST.

🎲

API Fuzz Testing

Fuzz testing sends random, unexpected, or malformed data to API endpoints to discover crashes, errors, and unexpected behavior. It's particularly effective at finding input validation issues and buffer overflows.

🔐

Authentication & Authorization Testing

Systematically testing authentication mechanisms (token validation, session management) and authorization rules (BOLA, BFLA). This is critical for APIs where access control is the primary defense.

🎯

Penetration Testing

Manual penetration testing involves skilled security professionals simulating targeted attacks. It excels at finding business logic flaws and chained exploits that automated tools miss. Should complement automated scanning.

📋

Contract Testing

Verifying that API implementations conform to their specifications (OpenAPI/Swagger). Deviations from the spec can introduce security vulnerabilities, especially around input validation and response formatting.

API Security Testing Checklist

Authentication

✓ Verify token validation on every endpoint
✓ Test for weak password policies
✓ Check session management and timeout
✓ Verify OAuth2/OIDC implementation
✓ Test for token leakage in logs/URLs

Authorization

✓ Test BOLA on every object endpoint
✓ Verify admin-only endpoints are protected
✓ Check field-level authorization
✓ Test for privilege escalation
✓ Verify cross-tenant isolation

Input Validation

✓ Test SQL injection on all parameters
✓ Test XSS in all input fields
✓ Check for SSRF in URL parameters
✓ Verify file upload restrictions
✓ Test for command injection

Configuration

✓ Check CORS policy
✓ Verify security headers (CSP, HSTS)
✓ Test for verbose error messages
✓ Check for default credentials
✓ Verify TLS configuration

Rate Limiting

✓ Test login endpoint rate limiting
✓ Verify API call rate limits
✓ Check for pagination on list endpoints
✓ Test payload size limits
✓ Verify timeout settings

API Security Testing Tools

Tool	Type	Free	Description
SEC Scanner	DAST	✓	Automated API security scanner with OWASP Top 10 coverage, PDF reports, and CI/CD integration. Best for continuous security testing.
Nuclei	DAST	✓	Open-source vulnerability scanner with 5000+ templates. The engine behind SEC Scanner's scanning capabilities.
OWASP ZAP	DAST	✓	Free web application security scanner with API support. Good for manual testing and scripting.
Burp Suite	DAST/Manual	✗	Professional web security testing platform with powerful API testing capabilities. Industry standard for manual pentesting.
Postman	Manual	✓	API development platform with testing features. Useful for manual API exploration and basic security checks.

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API Security Testing —Methods, Tools & Best Practices