CVE-2023-3825
📋 TL;DR
This vulnerability in PTC's KEPServerEX allows attackers to send specially crafted OPC UA messages containing recursively defined objects, causing uncontrolled resource consumption and potential denial-of-service crashes. It affects industrial control systems using KEPServerEX versions 6.0 through 6.14.263 for OPC UA communication.
💻 Affected Systems
- PTC KEPServerEX
📦 What is this software?
Kepserverex by Kepware
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption of KEPServerEX leading to loss of industrial process monitoring/control, potentially causing production downtime or safety issues in critical infrastructure.
Likely Case
Denial-of-service causing KEPServerEX to crash, disrupting OPC UA communications between industrial devices and control systems until service restart.
If Mitigated
Isolated impact limited to KEPServerEX service with no lateral movement or data compromise, with quick recovery via service restart.
🎯 Exploit Status
Exploitation requires network access to KEPServerEX OPC UA endpoint (typically port 49320). No authentication needed for the attack vector.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.14.264 and later
Vendor Advisory: https://www.ptc.com/en/support/article/CS362561
Restart Required: Yes
Instructions:
1. Download KEPServerEX version 6.14.264 or later from PTC support portal. 2. Backup current configuration. 3. Run installer to upgrade. 4. Restart KEPServerEX service.
🔧 Temporary Workarounds
Network Segmentation
windowsRestrict network access to KEPServerEX OPC UA endpoints to trusted sources only.
Windows Firewall: New-InboundFirewallRule -DisplayName 'Block KEPServerEX OPC UA' -Direction Inbound -LocalPort 49320 -Protocol TCP -Action Block
Protocol Disablement
windowsDisable OPC UA protocol if not required for operations.
KEPServerEX Configuration Manager: Navigate to Project > OPC UA > Disable OPC UA Server
🧯 If You Can't Patch
- Implement strict network access controls to KEPServerEX OPC UA endpoints (port 49320/TCP) using firewalls or network segmentation.
- Deploy intrusion detection systems to monitor for malformed OPC UA packets and implement rate limiting on OPC UA connections.
🔍 How to Verify
Check if Vulnerable:
Check KEPServerEX version in About dialog or registry: HKEY_LOCAL_MACHINE\SOFTWARE\PTC\KEPServerEX\VersionCheck Version:
reg query "HKLM\SOFTWARE\PTC\KEPServerEX" /v VersionVerify Fix Applied:
Verify version is 6.14.264 or higher and test OPC UA connectivity with valid clients.📡 Detection & Monitoring
Log Indicators:
- KEPServerEX service crashes or restarts
- High memory/CPU usage spikes in KEPServerEX process
- Windows Event Logs: Application errors from KEPServerEX
Network Indicators:
- Unusual volume of OPC UA traffic to port 49320
- Malformed OPC UA packets containing nested object definitions
- Connection attempts from unexpected sources to OPC UA endpoint
SIEM Query:
source="windows" AND (event_id=1000 OR event_id=1001) AND process_name="KEPServerEX.exe"