CVE-2024-50956
📋 TL;DR
A buffer overflow vulnerability in the RecvSocketData function of Inovance AM400 series PLCs allows attackers to cause denial of service or execute arbitrary code via specially crafted Modbus messages. This affects industrial control systems using specific versions of Inovance HCPLC_AM401, AM402, and AM403 controllers. Organizations using these PLCs in industrial environments are at risk.
💻 Affected Systems
- Inovance HCPLC_AM401-CPU1608TPTN
- Inovance HCPLC_AM402-CPU1608TPTN
- Inovance HCPLC_AM403-CPU1608TN
⚠️ 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
Remote code execution leading to complete PLC compromise, manipulation of industrial processes, physical damage, or safety incidents
Likely Case
Denial of service causing PLC crashes and disruption of industrial operations
If Mitigated
Limited impact if PLCs are isolated from untrusted networks and have proper network segmentation
🎯 Exploit Status
Public GitHub repository contains vulnerability details. Modbus protocol is unauthenticated by design, making exploitation straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Contact Inovance for firmware updates. 2. Backup PLC configuration. 3. Apply firmware update via programming software. 4. Restart PLC. 5. Verify functionality.
🔧 Temporary Workarounds
Network Segmentation
allIsolate PLCs from untrusted networks using firewalls
Modbus Port Restriction
linuxBlock external access to Modbus TCP port 502
iptables -A INPUT -p tcp --dport 502 -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to isolate PLCs from untrusted networks
- Deploy industrial firewall with deep packet inspection for Modbus traffic
🔍 How to Verify
Check if Vulnerable:
Check PLC firmware version via programming software or web interface. If version matches affected list, system is vulnerable.Check Version:
Use Inovance AutoShop programming software to read PLC version informationVerify Fix Applied:
Verify firmware version has been updated to a version not in the affected list📡 Detection & Monitoring
Log Indicators:
- PLC crash/restart events
- Unusual Modbus traffic patterns
- Buffer overflow errors in PLC logs
Network Indicators:
- Malformed Modbus packets to port 502
- Unusual source IPs accessing PLCs
- Excessive connection attempts
SIEM Query:
source_port:502 AND (packet_size > normal_threshold OR malformed_protocol:true)