CVE-2023-40756
📋 TL;DR
This vulnerability in PHPJabbers Callback Widget v1.0 allows attackers to enumerate valid user accounts through differences in password recovery messages. Attackers can identify which users exist in the system, enabling targeted brute force attacks. Organizations using this specific version of the callback widget are affected.
💻 Affected Systems
- PHPJabbers Callback Widget
📦 What is this software?
Callback Widget by Phpjabbers
⚠️ Risk & Real-World Impact
Worst Case
Attackers enumerate all valid users and conduct successful credential stuffing attacks, leading to account compromise and potential data breaches.
Likely Case
Attackers identify valid administrative or high-value user accounts and attempt password guessing attacks against those specific accounts.
If Mitigated
With rate limiting and account lockout policies, attackers can still enumerate users but cannot successfully brute force passwords.
🎯 Exploit Status
The vulnerability is simple to exploit by comparing password recovery response messages. No authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://www.phpjabbers.com/callback-widget/
Restart Required: No
Instructions:
No official patch available. Consider upgrading to a newer version if available or implementing workarounds.
🔧 Temporary Workarounds
Standardize Password Recovery Messages
allModify the password recovery functionality to return identical messages regardless of whether the user exists or not.
Edit PHP files to ensure consistent error/success messages in password recovery functions
Implement Rate Limiting
allAdd rate limiting to password recovery requests to prevent automated user enumeration.
Implement IP-based or session-based request throttling in PHP code
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to detect and block rapid password recovery attempts
- Monitor logs for unusual patterns of password recovery requests from single IP addresses
🔍 How to Verify
Check if Vulnerable:
Test password recovery with valid and invalid usernames. If response messages differ, the system is vulnerable.Check Version:
Check the PHPJabbers Callback Widget version in the admin panel or configuration filesVerify Fix Applied:
After implementing workarounds, test that password recovery returns identical messages for all username inputs.📡 Detection & Monitoring
Log Indicators:
- Multiple failed password recovery attempts for different usernames from same IP
- Unusual patterns of password recovery requests outside normal business hours
Network Indicators:
- High volume of POST requests to password recovery endpoint
- Requests with varying username parameters from single sources
SIEM Query:
source="web_logs" AND (uri_path="/password-recovery" OR uri_path="/forgot-password") AND status_code=200 | stats count by src_ip