CVE-2019-6557
📋 TL;DR
CVE-2019-6557 is a critical buffer overflow vulnerability in Moxa IKS and EDS industrial networking devices that allows remote attackers to execute arbitrary code. This affects organizations using these industrial control system (ICS) devices, potentially compromising critical infrastructure. The vulnerability stems from improper bounds checking in network services.
💻 Affected Systems
- Moxa IKS-G6824A
- Moxa IKS-G6824A-2GSFP
- Moxa EDS-405A
- Moxa EDS-408A
- Moxa EDS-510A
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of industrial control systems leading to operational disruption, data theft, or physical damage to critical infrastructure.
Likely Case
Remote code execution allowing attackers to install malware, pivot to other systems, or disrupt industrial operations.
If Mitigated
Limited impact with proper network segmentation and access controls preventing exploitation attempts.
🎯 Exploit Status
Exploitation requires network access to vulnerable services. Public exploit code exists making this easily weaponizable.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 4.5 and later
Vendor Advisory: https://www.moxa.com/en/support/product-support/security-advisory/moxa-iks-and-eds-series-industrial-ethernet-switches-buffer-overflow-vulnerability
Restart Required: Yes
Instructions:
1. Download firmware version 4.5 or later from Moxa website. 2. Backup current configuration. 3. Upload new firmware via web interface or CLI. 4. Reboot device. 5. Restore configuration if needed.
🔧 Temporary Workarounds
Network Segmentation
allIsolate vulnerable devices in separate network segments with strict firewall rules.
Access Control Lists
allImplement ACLs to restrict network access to vulnerable services (typically TCP ports 80, 443, 23).
access-list 100 deny tcp any any eq 80
access-list 100 deny tcp any any eq 443
access-list 100 deny tcp any any eq 23
access-list 100 permit ip any any
🧯 If You Can't Patch
- Remove internet exposure immediately and place behind firewalls with strict ingress/egress rules.
- Implement network monitoring and intrusion detection specifically for traffic to/from these devices.
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface (System > System Information) or CLI command 'show version'.Check Version:
show versionVerify Fix Applied:
Confirm firmware version is 4.5 or higher and verify no buffer overflow conditions in network services.📡 Detection & Monitoring
Log Indicators:
- Multiple connection attempts to device management ports
- Unusual process execution on device
- Configuration changes not initiated by administrators
Network Indicators:
- Unusual traffic patterns to device management ports (80, 443, 23)
- Buffer overflow patterns in network packets
- Exploit-specific payloads in traffic
SIEM Query:
source_ip="*" AND (dest_port=80 OR dest_port=443 OR dest_port=23) AND dest_ip="[device_ip]" AND bytes>threshold