IDOR Vulnerability Exploited: 2025 Bug Bounty Case Study on Broken Access Control & Privilege Escalation
By Satyam Pawale (@hackersatty)
About Me
IDOR Vulnerability
Hello all! My name is Satyam Pawale, or simply @hackersatty within the bug bounty space. I started my cybersecurity journey in 2024, and since then, I have committed to finding and reporting responsibly vulnerabilities that might otherwise lead to significant harm.
In this blog, I’d like to talk about a real-world vulnerability that I found—a non-authenticated API endpoint where sensitive shipping records could be deleted with no type of login. No credentials, no auth, just one unauthenticated call that could delete business-critical information.
Introduction
In today’s API-driven digital landscape, web applications depend heavily on robust access control mechanisms to protect sensitive resources. Unfortunately, even well-developed platforms can suffer from overlooked backend authorization flaws, such as IDOR (Insecure Direct Object Reference). This blog post uncovers a real-world case study where I discovered an IDOR vulnerability in a Password Bank feature that allowed unauthorized deletion of sensitive data, even after access was officially revoked.
This detailed breakdown includes my methodology, real examples, hands-on commands, and root cause analysis, and is written for bug bounty hunters, security researchers, and developers. It’s SEO-optimized, educational, and provides step-by-step insights into exploiting and fixing such vulnerabilities.
1. What is an IDOR Vulnerability?
IDOR vulnerability, short for Insecure Direct Object Reference, is a form of broken access control where an application exposes internal object references, such as user IDs or record numbers, and fails to validate whether the authenticated user has permission to access or modify them.
Examples of IDOR:
- Accessing
/user/1234/profileas/user/1235/profile - Changing invoice IDs to view others’ data
- Using outdated API tokens to interact with forbidden resources
According to OWASP Top 10, Broken Access Control — under which IDOR falls — is the most critical security issue today.
2. Understanding Broken Access Control in APIs
Broken Access Control occurs when restrictions on what authenticated users are allowed to do are not properly enforced. APIs, due to their headless nature and high privilege backend access, are prime targets.
Typical signs of broken access control:
- UI hides a feature, but API still accepts requests
- Session or token remains valid post permission changes
- Lack of backend role validation
3. Scope of the Vulnerable Application
Target: example.com
The platform offered a feature called Password Bank, where users could store login credentials. Access was role-based and could be revoked or upgraded by admins.
As a valid user, I initially had full rights to create, view, and delete entries in the Password Bank.
4. Recon & Initial Access (with Commands)
During initial testing, I followed a structured approach using tools like Burp Suite, curl, and Postman.
Step-by-step:
# Intercept the traffic with Burp Suite proxy
# Navigate to Password Bank in the UI
# Observe request when deleting a record
DELETE /api/password-bank/record/21345 HTTP/1.1
Host: example.com
Authorization: Bearer <your_JWT_token_here>
I saved this request using Burp’s “Send to Repeater” feature for later testing.
5. The Role Change & Feature Revocation
After a few days, my role was downgraded by the admin.
UI Impact:
- Password Bank disappeared
- Access buttons and CRUD features were disabled
Important Note: My session remained valid, and no logout or token refresh occurred.
6. Exploiting the Vulnerability IDOR vulnerability (Command Walkthrough)
I revisited the old DELETE request in Burp Repeater.
DELETE /api/password-bank/record/21345 HTTP/1.1
Host: example.com
Authorization: Bearer <still-active-JWT>
Response:
{
"message": "Password record deleted successfully."
}
Curl-based Replay:
curl -X DELETE https://example.com/api/password-bank/record/21345 \
-H "Authorization: Bearer <still-active-JWT>"
It worked! Despite having no UI access, the backend didn’t enforce proper role checks. This revealed a critical IDOR vulnerability and broken access control flaw.
7. Real-World Impact & Abuse Scenarios
The implications were severe:
- Ex-users could still delete records
- No logging or alerting was in place
- Backend assumed UI = access control
Attack Scenarios:
- Disgruntled employee deletes shared records
- Stealth deletion of 2FA or credentials
- Chaining forgotten API access for lateral movement
8. Privilege Escalation via Forgotten Endpoints
This is a textbook example of horizontal privilege escalation:
- My privileges were downgraded
- Yet I still had operational access to deletion
- This was never validated at the server level
Key Indicators:
- Forgotten endpoint
- No RBAC enforcement in backend
- Token not invalidated
9. Remediation Strategies & Developer Tips
Developers Should:
- Validate roles server-side on every request
- Revoke or reissue tokens on role changes
- Not rely on UI elements to enforce access
- Use central authorization middleware
- Maintain detailed access logs and alerts
- Integrate authorization testing into CI/CD pipelines
Example Fix (Pseudocode):
if not current_user.role.can_delete(record_id):
return Response("Unauthorized", 403)
10. Lessons for Bug Bounty Hunters
What Worked:
- Recording initial full-access requests
- Monitoring session persistence after role change
- Testing “removed” features manually via saved API calls
Recommended Tools:
- Burp Repeater for manual API replay
- Postman for token management and API testing
- JWT.io to decode and inspect session tokens
Keep an eye out for undocumented API endpoints, especially after permission downgrades.
11. Final Thoughts
This case reinforces the importance of backend role enforcement in web applications. UI-based revocation is not a security control.
A simple API replay revealed a high-impact vulnerability due to missing server-side checks. It serves as a reminder for developers to never rely solely on the frontend for enforcing user permissions.
Focus Keyword: IDOR vulnerability, broken access control, privilege escalation, API security bug, bug bounty case study
This blog is for educational purposes only. It provides insights into identifying and responsibly disclosing API vulnerabilities to improve application security.
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Resources:
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Final Thoughts: Keep Hunting, Keep Learning
This was one of my earliest critical bug bounty finds and taught me that Unauthenticated API Endpoint are one of the most vulnerable attack surfaces today. With tools like Swagger, Postman, and Burp Suite at your disposal, you don’t need to brute force—just observe and test logically.
🔍Unauthenticated API Endpoint is more than headers and tokens—it’s about understanding how developers structure access and how attackers think.
If you found this write-up helpful, feel free to connect with me on LinkedIn or follow my work on Twitter.
Until next time, stay curious and stay secure! 🔐