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Introduction:
Bug bounty hunting is a lucrative and rewarding field where cybersecurity researchers uncover vulnerabilities in systems before malicious actors exploit them. Gouri Sankar A, a Junior Software Developer and Bug Hunter, recently earned a $7,500 bounty from Microsoft by discovering an exposed endpoint—a critical security flaw. This article breaks down the techniques used, key cybersecurity commands, and how you can replicate this success.
Learning Objectives:
- Understand how manual reconnaissance helps uncover hidden vulnerabilities.
- Learn essential cybersecurity commands for endpoint testing.
- Discover best practices for responsible vulnerability disclosure.
1. Manual Reconnaissance: Finding Hidden Endpoints
Manual reconnaissance involves systematically probing a target for misconfigurations or exposed assets. Gouri likely used tools like curl and dirb to scan for endpoints.
Command:
curl -v https://target.com/api/v1/exposed-endpoint
Step-by-Step Guide:
- Use `curl -v` to inspect HTTP headers and responses.
- Look for 200 OK or 403 Forbidden responses, indicating accessible endpoints.
- If unauthorized, test for IDOR (Insecure Direct Object Reference) by manipulating parameters.
2. Testing for IDOR Vulnerabilities
IDOR occurs when an application exposes internal objects without proper authorization checks.
Command:
curl -X GET "https://target.com/api/user?id=12345" -H "Authorization: Bearer [bash]"
Step-by-Step Guide:
1. Replace `
` with a valid session token.</h2>
<ol>
<li>Change the `id` parameter to test access to other users' data. </li>
<li>If successful, report it as a critical vulnerability. </li>
</ol>
<h2 style="color: yellow;"> 3. Fuzzing for Hidden API Endpoints</h2>
<h2 style="color: yellow;">Automated fuzzing helps discover undocumented or forgotten endpoints.</h2>
<h2 style="color: yellow;"> Command (Using ffuf):</h2>
[bash]
ffuf -w wordlist.txt -u https://target.com/FUZZ -mc 200
Step-by-Step Guide:
- Use a wordlist (e.g., SecLists) to test common endpoint names.
2. Filter for HTTP 200 responses (`-mc 200`).
3. Analyze discovered endpoints for sensitive data exposure.
4. Checking for Misconfigured CORS
Misconfigured Cross-Origin Resource Sharing (CORS) can allow unauthorized domain access.
Command:
curl -H "Origin: https://evil.com" -I https://target.com/api/data
Step-by-Step Guide:
- Check if the server responds with
Access-Control-Allow-Origin:. - If it does, test if sensitive data can be stolen via JavaScript.
3. Report if the API allows arbitrary origins.
5. Exploiting & Reporting the Vulnerability
Once a flaw is found, ethical disclosure is crucial.
Steps:
1. Document the vulnerability with proof-of-concept (PoC) screenshots.
- Submit via the vendor’s bug bounty program (e.g., Microsoft Security Response Center).
- Follow responsible disclosure guidelines to avoid legal issues.
What Undercode Say:
- Key Takeaway 1: Manual testing combined with automated tools maximizes bug discovery.
- Key Takeaway 2: Proper documentation increases bounty payouts and credibility.
Analysis:
Gouri’s success highlights the importance of persistence in bug hunting. While automated scanners help, manual techniques often uncover high-impact flaws missed by tools. Microsoft’s bounty program rewards such findings, encouraging more researchers to improve global cybersecurity.
Prediction:
As APIs and cloud services grow, exposed endpoints will remain a top attack vector. Companies will invest more in bug bounty programs, making ethical hacking a high-demand skill. Researchers who master API security testing will lead the next wave of cybersecurity innovation.
Want to start bug hunting?
🔗 Microsoft Bug Bounty Program
🔗 Gouri’s Full Write-Up
Stay curious, stay secure. 🚀
IT/Security Reporter URL:
Reported By: G0w6y Just – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
