CVE-2024-44762
📋 TL;DR
This vulnerability in Webmin Usermin v2.100 allows attackers to distinguish between valid and invalid user accounts through differences in error messages during login attempts. This affects all systems running the vulnerable version of Webmin Usermin, enabling user enumeration attacks.
💻 Affected Systems
- Webmin Usermin
📦 What is this software?
Usermin by Webmin
⚠️ Risk & Real-World Impact
Worst Case
Attackers can enumerate all valid user accounts, then conduct targeted password attacks against known valid accounts, potentially leading to unauthorized access.
Likely Case
Attackers identify valid user accounts and use them for targeted phishing, credential stuffing, or brute force attacks.
If Mitigated
With proper monitoring and rate limiting, only limited user enumeration occurs without leading to successful account compromise.
🎯 Exploit Status
Exploitation requires no authentication and can be automated with simple scripts. The vulnerability is well-documented in public advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v2.101 or later
Vendor Advisory: https://webmin.com/security.html
Restart Required: Yes
Instructions:
1. Backup current configuration. 2. Download latest Usermin version from webmin.com. 3. Stop Usermin service. 4. Install new version. 5. Restart Usermin service. 6. Verify installation.
🔧 Temporary Workarounds
Implement Rate Limiting
linuxConfigure web server or application firewall to limit login attempts per IP address
# Example using iptables: iptables -A INPUT -p tcp --dport 20000 -m state --state NEW -m recent --set --name webmin
# iptables -A INPUT -p tcp --dport 20000 -m state --state NEW -m recent --update --seconds 60 --hitcount 10 --name webmin -j DROP
Modify Error Messages
allStandardize login error messages to prevent user enumeration
# Edit Usermin configuration to use identical error messages for all failed login attempts
🧯 If You Can't Patch
- Implement network-level controls to restrict access to Usermin interface
- Enable detailed logging and monitoring for suspicious login patterns
🔍 How to Verify
Check if Vulnerable:
Test login attempts with valid and invalid usernames - if error messages differ, system is vulnerableCheck Version:
cat /etc/webmin/usermin/versionVerify Fix Applied:
After patching, test that both valid and invalid usernames return identical error messages📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts with different usernames from same source
- Pattern of single failed attempt per username from same IP
Network Indicators:
- Unusual volume of POST requests to login endpoint
- Requests with sequential or dictionary usernames
SIEM Query:
source="usermin.log" AND "authentication failure" | stats count by src_ip, username | where count > 5