CVE-2023-39979
📋 TL;DR
This vulnerability allows remote attackers to bypass authentication in MXsecurity versions before 1.0.1 due to insufficient randomness in the web service authenticator. Affected systems are those running vulnerable MXsecurity versions, potentially exposing them to unauthorized access.
💻 Affected Systems
- MXsecurity
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to gain administrative access, modify configurations, exfiltrate sensitive data, or deploy ransomware.
Likely Case
Unauthorized access to the MXsecurity interface leading to configuration changes, data theft, or lateral movement within the network.
If Mitigated
Limited impact if strong network segmentation, monitoring, and additional authentication layers are in place.
🎯 Exploit Status
Authentication bypass vulnerabilities typically have low exploitation complexity once the method is understood.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.1
Vendor Advisory: https://www.moxa.com/en/support/product-support/security-advisory/mpsa-230403-mxsecurity-series-multiple-vulnerabilities
Restart Required: Yes
Instructions:
1. Download MXsecurity version 1.0.1 from Moxa support portal. 2. Backup current configuration. 3. Install the update following vendor documentation. 4. Restart the system. 5. Verify successful update.
🔧 Temporary Workarounds
Network Segmentation
linuxRestrict access to MXsecurity web interface to trusted IP addresses only.
iptables -A INPUT -p tcp --dport [MXSECURITY_PORT] -s [TRUSTED_IP] -j ACCEPT
iptables -A INPUT -p tcp --dport [MXSECURITY_PORT] -j DROP
Web Application Firewall
allDeploy WAF rules to detect and block authentication bypass attempts.
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure to trusted sources only.
- Enable detailed logging and monitoring for authentication attempts and alert on suspicious activity.
🔍 How to Verify
Check if Vulnerable:
Check MXsecurity web interface version in administration panel or via SSH: cat /etc/mxsecurity/versionCheck Version:
cat /etc/mxsecurity/version || grep version /opt/mxsecurity/version.txtVerify Fix Applied:
Confirm version shows 1.0.1 or higher and test authentication functionality.📡 Detection & Monitoring
Log Indicators:
- Failed authentication attempts followed by successful access from same IP
- Authentication logs showing successful login without proper credentials
- Unusual access patterns to administrative interfaces
Network Indicators:
- HTTP requests to authentication endpoints with unusual parameters
- Traffic to MXsecurity web interface from unexpected sources
SIEM Query:
source="mxsecurity" AND (event_type="auth_success" AND NOT user="[EXPECTED_USERS]")