CVE-2020-6981
📋 TL;DR
This vulnerability allows attackers to bypass authentication on Moxa EDS-G516E Series industrial switches running firmware version 5.2 or lower. Attackers can gain unauthorized access to the device's management interface without valid credentials. This affects industrial control systems and operational technology networks using these specific Moxa switches.
💻 Affected Systems
- Moxa EDS-G516E Series industrial Ethernet switches
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of industrial network switches allowing attackers to reconfigure network traffic, disrupt operations, or pivot to other critical systems in industrial environments.
Likely Case
Unauthorized access to switch management interface enabling network reconnaissance, configuration changes, or denial of service attacks against connected industrial equipment.
If Mitigated
Limited impact if switches are isolated in protected networks with strict access controls and monitoring, though authentication bypass remains possible.
🎯 Exploit Status
Authentication bypass vulnerabilities are typically easy to exploit. While no public PoC is documented, the vulnerability description suggests trivial exploitation requiring only network access to the device.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 5.3 or higher
Vendor Advisory: https://www.moxa.com/en/support/product-support/security-advisory/moxa-eds-g516e-series-multiple-web-server-vulnerabilities
Restart Required: Yes
Instructions:
1. Download firmware version 5.3 or higher from Moxa website. 2. Backup current configuration. 3. Upload new firmware via web interface or CLI. 4. Reboot switch. 5. Restore configuration if needed. 6. Verify firmware version is updated.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected switches in separate VLANs with strict firewall rules limiting access to management interfaces.
Access Control Lists
allImplement IP-based access control to restrict management interface access to authorized administrative networks only.
access-list 10 permit 192.168.1.0 0.0.0.255
line vty 0 4
access-class 10 in
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected switches from untrusted networks
- Deploy intrusion detection systems to monitor for unauthorized access attempts to switch management interfaces
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface (System > System Information) or CLI command 'show version'. If version is 5.2 or lower, device is vulnerable.Check Version:
show versionVerify Fix Applied:
Verify firmware version is 5.3 or higher. Test authentication by attempting to access management interface without credentials - should be denied.📡 Detection & Monitoring
Log Indicators:
- Failed authentication attempts followed by successful access
- Unauthorized IP addresses accessing management interface
- Configuration changes from unexpected sources
Network Indicators:
- HTTP/HTTPS traffic to switch management ports from unauthorized sources
- Unusual configuration commands sent to switch
SIEM Query:
source_ip NOT IN (authorized_admin_ips) AND dest_port IN (80,443,23) AND dest_ip IN (switch_ips)