CVE-2024-8936
📋 TL;DR
This CVE describes an Improper Input Validation vulnerability in Schneider Electric controllers that allows a Man-in-the-Middle attacker to send crafted Modbus function calls to tamper with controller memory. Successful exploitation could lead to loss of confidentiality of controller memory contents. This affects industrial control systems using vulnerable Schneider Electric products.
💻 Affected Systems
- Schneider Electric controllers with Modbus functionality
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of controller memory allowing unauthorized access to sensitive industrial process data, potential manipulation of control logic, and disruption of industrial operations.
Likely Case
Unauthorized access to controller memory contents revealing sensitive operational data and configuration information.
If Mitigated
Minimal impact with proper network segmentation, encrypted communications, and input validation controls in place.
🎯 Exploit Status
Exploitation requires Man-in-the-Middle position and knowledge of Modbus protocol. No authentication bypass needed as Modbus typically lacks authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to SEVD-2024-317-03 for specific patched versions
Vendor Advisory: https://download.schneider-electric.com/doc/SEVD-2024-317-03/SEVD-2024-317-03.pdf
Restart Required: Yes
Instructions:
1. Download firmware update from Schneider Electric portal. 2. Backup current configuration. 3. Apply firmware update following vendor instructions. 4. Restart controller. 5. Verify update successful.
🔧 Temporary Workarounds
Network Segmentation
allIsolate Modbus traffic to separate VLANs and restrict access to authorized systems only.
Modbus TCP Filtering
linuxImplement firewall rules to restrict Modbus TCP traffic (port 502) to authorized IP addresses only.
iptables -A INPUT -p tcp --dport 502 -s [authorized_ip] -j ACCEPT
iptables -A INPUT -p tcp --dport 502 -j DROP
🧯 If You Can't Patch
- Implement network segmentation to isolate Modbus traffic from untrusted networks
- Deploy industrial firewall with deep packet inspection for Modbus protocol validation
🔍 How to Verify
Check if Vulnerable:
Check controller firmware version against affected versions listed in SEVD-2024-317-03 advisory.Check Version:
Vendor-specific command; typically through HMI, web interface, or diagnostic tools provided by Schneider Electric.Verify Fix Applied:
Verify firmware version has been updated to patched version specified in vendor advisory.📡 Detection & Monitoring
Log Indicators:
- Unusual Modbus function codes
- Multiple failed Modbus requests
- Modbus traffic from unauthorized IP addresses
Network Indicators:
- Modbus traffic on unexpected ports
- Modbus traffic crossing network segments
- Unusual Modbus packet sizes
SIEM Query:
source_port:502 AND (function_code:NOT IN [1,2,3,4,5,6,15,16] OR packet_size > [threshold])