CVE-2023-38744
📋 TL;DR
A denial-of-service vulnerability exists in Omron CJ/CS Series industrial controllers due to improper input validation in their EtherNet/IP communication functions. Remote unauthenticated attackers can send specially crafted packets to crash affected units, disrupting industrial operations. This affects specific Omron PLC models with vulnerable firmware versions.
💻 Affected Systems
- CJ2M CPU Unit
- CJ2H CPU Unit
- CS/CJ Series EtherNet/IP Unit CS1W-EIP21
- CS/CJ Series EtherNet/IP Unit CJ1W-EIP21
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Critical industrial processes are halted, causing production downtime, safety system failures, or equipment damage in manufacturing environments.
Likely Case
Targeted PLC units become unresponsive, requiring manual restart and causing temporary production interruptions.
If Mitigated
With network segmentation and proper controls, impact is limited to isolated network segments with minimal operational disruption.
🎯 Exploit Status
Attack requires network access to EtherNet/IP port (typically TCP/44818). No authentication needed. Crafting malicious packets requires understanding of EtherNet/IP protocol.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: CJ2M: Update to later than Ver. 2.18, CJ2H: Update to later than Ver. 3.04, CS1W-EIP21/CJ1W-EIP21: Update to later than V3.04
Vendor Advisory: https://www.ia.omron.com/product/vulnerability/OMSR-2023-006_en.pdf
Restart Required: Yes
Instructions:
1. Download firmware update from Omron support portal. 2. Connect to PLC via programming cable. 3. Backup current program and settings. 4. Upload new firmware using CX-Programmer or similar tool. 5. Restart PLC and verify operation.
🔧 Temporary Workarounds
Network Segmentation
allIsolate EtherNet/IP ports from untrusted networks using firewalls or VLANs
Port Restriction
allBlock TCP port 44818 at network perimeter for all non-essential traffic
🧯 If You Can't Patch
- Implement strict network access controls to limit EtherNet/IP traffic to trusted sources only
- Deploy intrusion detection systems to monitor for anomalous EtherNet/IP traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check firmware version via CX-Programmer software or physical unit labels. Verify if EtherNet/IP functionality is enabled.Check Version:
Use CX-Programmer: Connect to PLC → PLC Information → Check Unit VersionVerify Fix Applied:
After update, confirm firmware version exceeds vulnerable versions. Test EtherNet/IP communication functionality.📡 Detection & Monitoring
Log Indicators:
- PLC error logs showing communication failures
- Unexpected PLC restarts or fault conditions
Network Indicators:
- Unusual traffic patterns to TCP/44818
- Malformed EtherNet/IP packets from untrusted sources
SIEM Query:
source_port:44818 AND (packet_size:<100 OR packet_size:>1500) OR protocol:enip AND anomaly_score:>7