API Fuzzing for Bug Bounty

Purpose

Provide comprehensive techniques for testing REST, SOAP, and GraphQL APIs during bug bounty hunting and penetration testing engagements. Covers vulnerability discovery, authentication bypass, IDOR exploitation, and API-specific attack vectors.

Inputs/Prerequisites

• Burp Suite or similar proxy tool
• API wordlists (SecLists, api_wordlist)
• Understanding of REST/GraphQL/SOAP protocols
• Python for scripting
• Target API endpoints and documentation (if available)

Outputs/Deliverables

• Identified API vulnerabilities
• IDOR exploitation proofs
• Authentication bypass techniques
• SQL injection points
• Unauthorized data access documentation

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API Types Overview

Type	Protocol	Data Format	Structure
SOAP	HTTP	XML	Header + Body
REST	HTTP	JSON/XML/URL	Defined endpoints
GraphQL	HTTP	Custom Query	Single endpoint

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Core Workflow

🧠 Knowledge Modules (Fractal Skills)

1. Step 1: API Reconnaissance

2. Step 2: Authentication Testing

3. Step 3: IDOR Testing

4. Step 4: Injection Testing

5. Step 5: Method Testing

6. Introspection Query

7. GraphQL IDOR

8. GraphQL SQL/NoSQL Injection

9. Rate Limit Bypass (Batching)

10. GraphQL DoS (Nested Queries)

11. GraphQL XSS

12. GraphQL Tools

13. PDF Export Attacks

14. DoS via Limits

15. Example 1: IDOR Exploitation

16. Example 2: GraphQL Introspection