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Introduction:
In modern web applications, access control mechanisms are the final gatekeepers protecting sensitive administrative functions. A recent bug bounty discovery highlights how a trivial oversight in endpoint authorization can allow a standard user to escalate privileges and execute devastating admin-level actions. This vulnerability, known as Broken Access Control, remains a top-tier web security risk according to the OWASP Top 10.
Learning Objectives:
- Understand the mechanics of path-based access control vulnerabilities
- Learn to test for and identify authorization flaws in API endpoints
- Implement secure coding practices to prevent privilege escalation attacks
You Should Know:
- Intercepting and Modifying HTTP Requests with Burp Suite
To test for access control vulnerabilities, security professionals use intercepting proxies to capture and manipulate web traffic.Step 1: Configure browser to use Burp Suite as proxy (usually 127.0.0.1:8080) Step 2: Navigate to target application and perform normal user actions Step 3: Turn on interception in Burp Suite Proxy tab Step 4: Perform the action (e.g., click "Delete Account") and capture the request Step 5: Modify the request path or parameters to target admin endpoints Step 6: Forward the modified request and observe server response
This methodology allows testers to verify whether the server properly validates user permissions before processing requests.
2. Essential cURL Commands for Manual API Testing
When automated tools aren’t sufficient, manual testing with cURL provides precise control over HTTP requests.
curl -X POST 'https://target.com/user/delete' \
-H 'Authorization: Bearer <user_token>' \
-H 'Content-Type: application/json' \
-d '{"user_id":"123"}'
curl -X POST 'https://target.com/admin/delete' \
-H 'Authorization: Bearer <same_user_token>' \
-H 'Content-Type: application/json' \
-d '{"user_id":"123"}'
The second command tests if the same user token can access admin endpoints. If both return success, a broken access control vulnerability exists.
3. Linux Command Line Reconnaissance for API Endpoints
Before testing access controls, you must discover available endpoints through various methods.
grep -r "admin/delete" /path/to/webapp/source/ Search source code nikto -h https://target.com -output nikto_scan.txt Web vulnerability scanner dirb https://target.com /usr/share/dirb/wordlists/common.txt Directory brute force ffuf -w wordlist.txt -u https://target.com/FUZZ Fast web fuzzer
These commands help identify potential administrative endpoints that might be vulnerable to access control bypass.
4. Windows PowerShell for Web Request Testing
PowerShell provides native capabilities for testing web applications and APIs.
$headers = @{Authorization = "Bearer $userToken"}
$body = @{user_id = "123"} | ConvertTo-Json
Test user endpoint
Invoke-RestMethod -Uri "https://target.com/user/delete" -Method Post -Headers $headers -Body $body
Test admin endpoint with same token
Invoke-RestMethod -Uri "https://target.com/admin/delete" -Method Post -Headers $headers -Body $body
Compare the responses from both requests. If the admin endpoint accepts the regular user’s token, the access control is broken.
5. Database Query Analysis for Role Verification
Broken access control often stems from inadequate database role checking in the application logic.
-- Vulnerable query (checks if user exists but not role) DELETE FROM accounts WHERE user_id = $input_id; -- Secure query (checks user role) DELETE FROM accounts WHERE user_id = $input_id AND role = 'admin'; -- Alternative secure approach IF (SELECT role FROM users WHERE id = $current_user) = 'admin' THEN DELETE FROM accounts WHERE user_id = $input_id; END IF;
Developers must verify both authentication AND authorization at every privileged endpoint.
6. Web Application Firewall (WAF) Bypass Techniques
Attackers may need to bypass security controls to exploit access control vulnerabilities.
Original blocked request POST /admin/delete HTTP/1.1 Bypass techniques POST /aDmIn/delete HTTP/1.1 Case variation POST /admin%2fdelete HTTP/1.1 URL encoding POST /admin/../admin/delete HTTP/1.1 Path traversal POST /api/v1/admin/delete HTTP/1.1 Alternative path
Security teams should implement normalized path processing and consistent authorization checks.
7. Automated Testing with Python Scripts
For comprehensive testing, automated scripts can systematically check for access control issues.
import requests
def test_access_control(base_url, token, endpoints):
headers = {'Authorization': f'Bearer {token}'}
for endpoint in endpoints:
response = requests.post(f"{base_url}{endpoint}",
headers=headers,
json={"user_id": "test"})
if response.status_code == 200:
print(f"VULNERABLE: {endpoint} accessible with user token")
Usage
test_access_control('https://target.com', user_token,
['/user/delete', '/admin/delete', '/api/admin/users'])
This script automates the discovery process, efficiently identifying endpoints lacking proper authorization.
What Undercode Say:
- The simplicity of this vulnerability demonstrates how complex authorization systems can fail through basic oversights
- Organizations must implement role verification at the framework level rather than relying on developers to remember it for each endpoint
- Regular automated security testing should include comprehensive access control verification across all user roles
The discovered vulnerability follows a common pattern where developers protect the UI but neglect server-side authorization. The visual “Delete Account” button appeared for regular users, but the underlying assumption was that only admins could access the `/admin/delete` endpoint. This security-through-obscurity approach fails against determined attackers. Modern applications require systematic authorization checks that verify user roles against requested actions at the API gateway, middleware, and database layers. The economic impact of such vulnerabilities can be catastrophic, enabling mass account deletion or unauthorized administrative actions.
Prediction:
As applications continue to migrate toward microservices and API-driven architectures, broken access control vulnerabilities will increasingly become the primary attack vector for data breaches. The proliferation of poorly implemented role-based access control (RBAC) systems will lead to massive-scale privilege escalation incidents affecting millions of users. Within two years, we predict automated access control testing will become mandatory in DevSecOps pipelines, and AI-powered static analysis tools will emerge specifically to identify authorization flaws before deployment. The cybersecurity industry will shift focus from perimeter defense to internal authorization enforcement as the last line of defense.
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: Sheshank Shekhar – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
