CVE-2020-6991
📋 TL;DR
This vulnerability in Moxa EDS-G516E Series firmware allows attackers to brute-force weak passwords to gain unauthorized access. It affects industrial network equipment running firmware version 5.2 or lower. The high CVSS score indicates critical risk requiring immediate attention.
💻 Affected Systems
- Moxa EDS-G516E Series
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of industrial network equipment allowing attackers to disrupt operations, modify configurations, or use as pivot point into OT networks.
Likely Case
Unauthorized access to network devices enabling configuration changes, traffic interception, or denial of service.
If Mitigated
Limited impact with strong password policies and network segmentation preventing brute-force attempts.
🎯 Exploit Status
Brute-force attacks require no authentication and can be automated with common tools.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 5.3 or higher
Vendor Advisory: https://www.moxa.com/en/support/product-support/security-advisory/moxa-eds-g516e-series-firmware-vulnerability
Restart Required: Yes
Instructions:
1. Download firmware version 5.3 or higher from Moxa website. 2. Backup current configuration. 3. Upload and install new firmware via web interface or CLI. 4. Reboot device. 5. Restore configuration if needed.
🔧 Temporary Workarounds
Implement Strong Password Policy
allEnforce complex passwords with minimum length and character requirements
Enable Account Lockout
allConfigure account lockout after failed login attempts
🧯 If You Can't Patch
- Isolate vulnerable devices in separate VLAN with strict firewall rules
- Implement network-based intrusion detection to monitor for brute-force attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface (System > Maintenance > Firmware) or CLI command 'show version'Check Version:
show versionVerify Fix Applied:
Confirm firmware version is 5.3 or higher and test password complexity requirements📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts from single IP
- Successful logins from unusual locations/times
Network Indicators:
- Rapid authentication attempts to device management interface
- Traffic patterns matching brute-force tools
SIEM Query:
source="eds-g516e" AND (event_type="authentication_failure" count>10 within 5min)