CVE-2021-29242
📋 TL;DR
CVE-2021-29242 is an improper input validation vulnerability in CODESYS Control Runtime systems that allows attackers to send crafted packets to manipulate the router's addressing scheme. This can enable attackers to reroute, add, remove, or modify low-level communication packages. Organizations using CODESYS Control Runtime for industrial automation and control systems are affected.
💻 Affected Systems
- CODESYS Control Runtime
📦 What is this software?
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⚠️ Risk & Real-World Impact
Worst Case
Attackers could manipulate industrial control system communications to cause physical damage, disrupt critical processes, or create safety hazards by altering control commands.
Likely Case
Attackers could disrupt industrial operations, cause production downtime, or manipulate data flows to hide malicious activities.
If Mitigated
With proper network segmentation and monitoring, impact would be limited to communication disruptions within isolated network segments.
🎯 Exploit Status
Exploitation requires network access to CODESYS communication ports and knowledge of the protocol.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.5.17.0 and later
Vendor Advisory: https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=14640&token=623b6fceb0579ef0f7505e29beefa5b3f8ac7873&download=
Restart Required: Yes
Instructions:
1. Download CODESYS Control Runtime version 3.5.17.0 or later from CODESYS customer portal. 2. Backup current configuration. 3. Install the update following vendor instructions. 4. Restart the system. 5. Verify functionality.
🔧 Temporary Workarounds
Network Segmentation
allIsolate CODESYS systems in dedicated network segments with strict firewall rules.
Communication Port Restrictions
allRestrict access to CODESYS communication ports (typically 1217, 1740-1743) to trusted systems only.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate CODESYS systems from untrusted networks
- Deploy intrusion detection systems to monitor for anomalous communication patterns
🔍 How to Verify
Check if Vulnerable:
Check CODESYS Control Runtime version via CODESYS IDE or system information tools. Versions below 3.5.17.0 are vulnerable.Check Version:
Check via CODESYS IDE: Project → Device → Device Information or system-specific commands depending on platform.Verify Fix Applied:
Verify version is 3.5.17.0 or higher and test communication functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual communication patterns
- Unexpected router configuration changes
- Failed authentication attempts on CODESYS ports
Network Indicators:
- Malformed packets to CODESYS ports (1217, 1740-1743)
- Unexpected routing changes in industrial network traffic
SIEM Query:
source_port:1217 OR source_port:1740-1743 AND (packet_size:anomalous OR protocol_violation:true)🔗 References
- https://customers.codesys.com/index.php
- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=14640&token=623b6fceb0579ef0f7505e29beefa5b3f8ac7873&download=
- https://www.codesys.com/security/security-reports.html
- https://customers.codesys.com/index.php
- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=14640&token=623b6fceb0579ef0f7505e29beefa5b3f8ac7873&download=
- https://www.codesys.com/security/security-reports.html
