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IDOR (Insecure Direct Object Reference) is a common web vulnerability that occurs when an application provides direct access to objects (files, data, database entries) based on user-supplied input without proper authorization checks. Attackers can manipulate references (e.g., changing an ID in a URL) to access unauthorized data.
You Should Know:
How IDOR Works
- Applications expose internal object references (e.g.,
/user/profile?id=123). - Attackers modify the `id` parameter to access other users’ data (e.g.,
/user/profile?id=124). - Lack of server-side validation leads to unauthorized access.
Types of IDOR Attacks
- Horizontal IDOR: Accessing data of other users at the same privilege level.
– Example: Changing `account_id=100` to account_id=101.
2. Vertical IDOR: Escalating privileges to access admin functions.
– Example: Modifying `role=user` to role=admin.
Exploiting IDOR
Example Request:
GET /api/user?uid=100 HTTP/1.1 Host: vulnerable.com
Modify `uid=100` to `uid=101` to fetch another user’s data.
Preventing IDOR
- Implement Access Control: Verify user permissions for every request.
- Use Indirect References: Map user input to internal IDs (e.g., UUIDs instead of sequential numbers).
- Token-Based Authorization: Require session tokens for sensitive operations.
Practice Commands & Code
1. Manual Testing with cURL:
curl -s "https://vulnerable.com/api/user?uid=100" -H "Cookie: session=valid_token"
Change `uid` to test for IDOR.
2. Automated Testing with Python:
import requests
for user_id in range(100, 110):
response = requests.get(f"https://vulnerable.com/api/user?uid={user_id}")
if response.status_code == 200:
print(f"Data leaked for UID {user_id}: {response.text}")
3. Burp Suite Testing:
- Intercept a request containing an object reference.
- Send to Repeater and modify parameters.
- Check if unauthorized access is possible.
4. Linux Command for Log Analysis:
grep "uid=" /var/log/nginx/access.log | awk '{print $7}' | sort | uniq -c
Detects suspicious parameter tampering.
5. Windows Command for Access Control Checks:
Get-Acl -Path "C:\SensitiveData" | Format-List
Ensures proper file permissions.
What Undercode Say
IDOR remains a critical flaw due to poor access control implementations. Always enforce server-side validation, avoid exposing direct references, and conduct regular security audits. Tools like Burp Suite, OWASP ZAP, and custom scripts help detect IDOR early.
Expected Output:
- Unauthorized data access if IDOR exists.
- 403 Forbidden if proper controls are in place.
- Logs showing parameter manipulation attempts.
Relevant Course Links:
References:
Reported By: Zlatanh Idor – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
