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In this article, we explore advanced API testing techniques used in bug bounty hunting, including HTTP method manipulation, IDOR, CORS misconfigurations, and more. Below are verified commands, tools, and steps to replicate these tests.
You Should Know:
1. Extraneous Parameters Testing
Check how APIs handle unexpected parameters. Use `curl` or `Burp Suite` to send additional parameters:
curl -X GET "https://target.com/api/user?param1=value1&unexpected_param=test" -H "Authorization: Bearer token"
2. HTTP Method Manipulation
Test if APIs accept unintended methods (e.g., GET instead of POST):
curl -X GET "https://target.com/api/delete_user" -H "Authorization: Bearer token"
3. Parameter Pollution
Send duplicate parameters to exploit parsing inconsistencies:
curl -X POST "https://target.com/api/update?user_id=123&user_id=456" -d "data=malicious"
4. Case Sensitivity Testing
Check if endpoints are case-sensitive:
curl -X GET "https://target.com/API/User" -H "Authorization: Bearer token"
5. Auth Bypass via Missing/Null Tokens
Test token validation weaknesses:
curl -X GET "https://target.com/api/admin" -H "Authorization: "
6. IDOR via Sequential IDs
Brute-force sequential IDs to access unauthorized data:
for id in {1..100}; do curl -X GET "https://target.com/api/user/$id"; done
7. Overly Permissive CORS
Check misconfigured CORS headers:
curl -I -X OPTIONS "https://target.com/api/data" -H "Origin: https://evil.com"
8. Replay Old/Used Tokens
Test if expired tokens still work:
curl -X GET "https://target.com/api/data" -H "Authorization: Bearer old_token"
9. Verbose Error Messages
Trigger errors to extract sensitive info:
curl -X GET "https://target.com/api/invalid_endpoint"
10. Rate Limiting Bypass
Test rate limits by sending multiple requests:
for i in {1..100}; do curl -X POST "https://target.com/api/login"; done
11. Method Override via Query Parameter
Some APIs allow method override:
curl -X POST "https://target.com/api/action?_method=DELETE"
What Undercode Say
Bug bounty hunting requires persistence, creativity, and automation. The techniques above help uncover API flaws, but chaining them increases impact. Always document findings clearly and follow responsible disclosure.
Expected Output:
- 30+ bugs found (mostly low-severity)
- Focus on chaining vulnerabilities for higher impact
- Automate repetitive tests with tools like
Burp Suite,Postman, and custom scripts
Prediction
As APIs grow, vulnerabilities like insecure direct object references (IDOR) and broken authentication will remain prevalent. Automation and AI-assisted bug hunting will become standard in the next 3 years.
Relevant URLs:
IT/Security Reporter URL:
Reported By: Activity 7334154061413273601 – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
