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In a recent bug bounty discovery, an Insecure Direct Object Reference (IDOR) vulnerability was found in a newsletter subscription system, allowing unauthorized access to user emails and the ability to mass-unsubscribe users. The vulnerable endpoint was:
🔗 `example.com/newsletter/{id}`
By simply altering the `{id}` parameter, an attacker could:
– View other users’ email addresses
– Unsubscribe any user from the newsletter
– Potentially unsubscribe all subscribers in bulk
You Should Know: How to Test and Mitigate IDOR Vulnerabilities
1. Identifying IDOR Vulnerabilities
Use these methods to detect IDOR flaws:
- Manual Testing: Change parameter values (e.g., `user_id=100` →
user_id=101). - Burp Suite: Intercept requests and modify IDs.
- Automated Scanners: Tools like OWASP ZAP or Burp Scanner can help detect IDOR.
2. Exploiting IDOR (Proof of Concept)
[http]
GET /newsletter/123 HTTP/1.1
Host: example.com
Authorization: Bearer
[/http]
– Replace `123` with another user’s ID to test access control.
3. Mitigation Techniques
- Implement Access Control Checks:
if request.user != newsletter.user: raise PermissionDenied
- Use UUIDs Instead of Sequential IDs:
id = uuid.uuid4() Generates a random UUID
- Rate Limiting: Prevent mass-unsubscription attacks.
4. Linux Commands for Security Testing
- Check Open DNS Resolvers:
nmap -sU -p 53 --script=dns-recursion <target>
- Monitor HTTP Traffic:
tcpdump -i eth0 'port 80' -w http_traffic.pcap
5. Windows Command for Log Analysis
- Extract Suspicious IPs from Logs:
Get-Content .\access.log | Select-String "POST /newsletter"
What Undercode Say
IDOR remains a critical vulnerability due to poor access control implementations. Always:
– Validate user permissions at every endpoint.
– Avoid exposing sequential IDs—use hashes or UUIDs.
– Log and monitor unusual subscription changes.
Expected Output: A secure newsletter system where user data remains private and actions are permission-bound.
Relevant URLs:
References:
Reported By: Qaziabdullahalam Total – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
