CVE-2020-5531
📋 TL;DR
This critical vulnerability in Mitsubishi Electric industrial controllers allows remote attackers to cause denial of service or execute arbitrary malware via unspecified vectors. Affected systems include MELSEC C Controller Module, MELIPC Series MI5000, MELSEC-Q Series, and MELSEC iQ-R Series controllers with specific serial numbers or firmware versions.
💻 Affected Systems
- Mitsubishi Electric MELSEC C Controller Module
- MELIPC Series MI5000
- MELSEC-Q Series C Controller Module (Q24DHCCPU-V, Q24DHCCPU-VG)
- MELSEC iQ-R Series C Controller Module / C Intelligent Function Module (R12CCPU-V, RD55UP06-V)
📦 What is this software?
Mi5122 Vw Firmware by Mitsubishielectric
Q24dhccpu V Firmware by Mitsubishielectric
Q24dhccpu Vg Firmware by Mitsubishielectric
R12ccpu V Firmware by Mitsubishielectric
Rd55up06 V Firmware by Mitsubishielectric
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing malware execution, potential disruption of industrial processes, and unauthorized access to control systems.
Likely Case
Denial of service attacks disrupting industrial operations and potential malware deployment affecting controller functionality.
If Mitigated
Limited impact if systems are isolated behind firewalls with strict network segmentation and access controls.
🎯 Exploit Status
CVSS 9.8 with Attack Vector: Network, Attack Complexity: Low, Privileges Required: None, User Interaction: None indicates easy remote exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Updated firmware versions beyond affected serial number ranges
Vendor Advisory: https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2019-003_en.pdf
Restart Required: Yes
Instructions:
1. Check controller serial numbers and firmware versions. 2. Contact Mitsubishi Electric for firmware updates. 3. Apply firmware updates following vendor instructions. 4. Restart controllers after update. 5. Verify update completion.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected controllers in separate network segments with strict firewall rules
Access Control Lists
allImplement strict ACLs to limit network access to controller Ethernet ports
🧯 If You Can't Patch
- Physically isolate controllers from untrusted networks and implement air-gapping where possible
- Implement network monitoring and intrusion detection specifically for industrial control system traffic
🔍 How to Verify
Check if Vulnerable:
Check controller serial numbers and firmware versions against affected ranges specified in vendor advisoryCheck Version:
Use Mitsubishi Electric configuration tools or check physical controller labels for serial numbers and firmware versionsVerify Fix Applied:
Verify serial numbers are outside affected ranges or firmware has been updated to non-vulnerable versions📡 Detection & Monitoring
Log Indicators:
- Unexpected network connections to controller Ethernet ports
- Unusual traffic patterns to industrial controllers
- Controller restart or malfunction logs
Network Indicators:
- Unusual traffic to TCP/UDP ports on industrial controllers
- Malformed packets targeting controller IP addresses
- Traffic from unexpected sources to controller networks
SIEM Query:
source_ip IN (controller_ips) AND (protocol_anomaly = true OR connection_count > threshold)