CVE-2020-13556
📋 TL;DR
CVE-2020-13556 is a critical out-of-bounds write vulnerability in the OpENer Ethernet/IP server that allows remote code execution via specially crafted network requests. This affects systems running vulnerable versions of OpENer, potentially allowing attackers to take complete control of affected devices. Industrial control systems and embedded devices using this stack are particularly at risk.
💻 Affected Systems
- EIP Stack Group OpENer
📦 What is this software?
Opener by Opener Project
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise leading to ransomware deployment, data theft, or disruption of industrial processes
Likely Case
Remote code execution allowing attacker to install malware, pivot to other systems, or disrupt operations
If Mitigated
Limited impact if network segmentation and access controls prevent exploitation attempts
🎯 Exploit Status
Detailed technical analysis available in Talos reports; exploitation requires sending crafted network packets
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 2.4 or later
Vendor Advisory: https://github.com/EIPStackGroup/OpENer
Restart Required: Yes
Instructions:
1. Download latest version from GitHub repository 2. Replace vulnerable OpENer installation 3. Restart affected services 4. Verify version is 2.4 or higher
🔧 Temporary Workarounds
Network Segmentation
linuxIsolate OpENer instances from untrusted networks
iptables -A INPUT -p tcp --dport 44818 -j DROP
iptables -A INPUT -p udp --dport 2222 -j DROP
Access Control Lists
windowsRestrict network access to OpENer services
netsh advfirewall firewall add rule name="Block OpENer" dir=in action=block protocol=TCP localport=44818
🧯 If You Can't Patch
- Implement strict network segmentation to isolate vulnerable systems
- Deploy intrusion detection systems to monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check OpENer version and compare against vulnerable versions (2.3 or development commit 8c73bf3)Check Version:
Check application logs or build information for version stringVerify Fix Applied:
Confirm OpENer version is 2.4 or higher and no longer contains the vulnerable code📡 Detection & Monitoring
Log Indicators:
- Unusual network connections to port 44818
- Multiple malformed packet errors
- Process crashes or unexpected restarts
Network Indicators:
- Crafted Ethernet/IP packets targeting the vulnerability
- Unusual traffic patterns to industrial control ports
SIEM Query:
source="network" dest_port=44818 AND (packet_size>normal OR malformed_packet=true)