CVE-2018-11420
📋 TL;DR
CVE-2018-11420 is a critical memory corruption vulnerability in the web interface of Moxa OnCell G3100-HSPA Series cellular gateways. Attackers can exploit this to execute arbitrary code or cause denial of service. Organizations using affected Moxa cellular gateways with internet-facing web interfaces are at risk.
💻 Affected Systems
- Moxa OnCell G3100-HSPA Series
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, lateral movement into connected networks, and persistent backdoor installation.
Likely Case
Remote code execution allowing attackers to reconfigure devices, intercept network traffic, or use devices as attack platforms.
If Mitigated
Denial of service if exploit fails or is blocked by network controls, but device functionality may still be disrupted.
🎯 Exploit Status
Memory corruption vulnerabilities in web interfaces often have reliable exploitation paths. Public advisory includes technical details that could facilitate exploit development.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 1.6 or later
Vendor Advisory: https://www.moxa.com/en/support/product-support/security-advisory/oncell-g3100-hspa-series-web-server-memory-corruption-vulnerability
Restart Required: Yes
Instructions:
1. Download firmware version 1.6 or later from Moxa support portal. 2. Backup current configuration. 3. Upload new firmware via web interface. 4. Reboot device. 5. Restore configuration if needed.
🔧 Temporary Workarounds
Disable web interface
allDisable the vulnerable web interface if not required for operations
Configuration via CLI: configure terminal
no web-server enable
Network segmentation
linuxRestrict access to web interface using firewall rules
iptables -A INPUT -p tcp --dport 80 -s trusted_network -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s trusted_network -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Isolate affected devices in separate network segment with strict firewall rules
- Implement network-based intrusion detection to monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface at System > Maintenance > Firmware or via CLI command: show versionCheck Version:
show versionVerify Fix Applied:
Confirm firmware version is 1.6 or higher using same methods📡 Detection & Monitoring
Log Indicators:
- Web interface crash logs
- Unexpected process creation
- Memory allocation errors in system logs
Network Indicators:
- Unusual HTTP requests to web interface
- Traffic patterns suggesting exploit payload delivery
SIEM Query:
source="moxa-gateway" AND (event_type="crash" OR event_type="memory_error" OR http_request MATCHES "malicious_pattern")