CVE-2021-30194
📋 TL;DR
CVE-2021-30194 is an out-of-bounds read vulnerability in CODESYS V2 Web-Server that could allow attackers to read sensitive memory contents or cause denial of service. This affects industrial control systems using CODESYS V2 Web-Server versions before 1.1.9.20. The vulnerability is remotely exploitable with a CVSS score of 9.1, indicating critical severity.
💻 Affected Systems
- CODESYS V2 Web-Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, manipulation of industrial processes, or data exfiltration from memory
Likely Case
Denial of service causing PLC/controller disruption or information disclosure from memory reads
If Mitigated
Limited impact if proper network segmentation and access controls prevent external exploitation
🎯 Exploit Status
Out-of-bounds read vulnerabilities typically require less sophistication to exploit than write vulnerabilities, but exploitation details are not publicly documented
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.1.9.20
Vendor Advisory: https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=14726&token=553da5d11234bbe1ceed59969d419a71bb8c8747&download=
Restart Required: Yes
Instructions:
1. Download CODESYS V2 Web-Server version 1.1.9.20 or later from CODESYS customer portal. 2. Stop the CODESYS runtime. 3. Install the updated web server component. 4. Restart the CODESYS runtime. 5. Verify the version is 1.1.9.20 or higher.
🔧 Temporary Workarounds
Disable Web Server
allDisable the CODESYS V2 Web-Server component if not required for operations
Configure CODESYS runtime to disable web server functionality through configuration settings
Network Segmentation
allRestrict network access to CODESYS systems using firewalls or network segmentation
Add firewall rules to block external access to CODESYS web server ports (typically 80/443)
🧯 If You Can't Patch
- Implement strict network segmentation to isolate CODESYS systems from untrusted networks
- Deploy intrusion detection systems to monitor for exploitation attempts and anomalous traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check CODESYS V2 Web-Server version via web interface or configuration files. If version is below 1.1.9.20, system is vulnerable.Check Version:
Access CODESYS web interface or check runtime configuration for version informationVerify Fix Applied:
Verify CODESYS V2 Web-Server version is 1.1.9.20 or higher after applying patch📡 Detection & Monitoring
Log Indicators:
- Unusual web server access patterns
- Memory access errors in system logs
- Web server crash or restart events
Network Indicators:
- Unusual HTTP requests to CODESYS web endpoints
- Traffic patterns suggesting memory probing
SIEM Query:
source="CODESYS" AND (event="web_server_error" OR event="memory_access") OR destination_port IN (80, 443) AND source_ip NOT IN (trusted_networks)🔗 References
- https://customers.codesys.com/index.php
- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=14726&token=553da5d11234bbe1ceed59969d419a71bb8c8747&download=
- https://customers.codesys.com/index.php
- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=14726&token=553da5d11234bbe1ceed59969d419a71bb8c8747&download=
