CVE-2020-5653
📋 TL;DR
A buffer overflow vulnerability in the TCP/IP function of Mitsubishi Electric MELSEC iQ-R series modules allows remote unauthenticated attackers to crash network functions or execute arbitrary code via specially crafted packets. This affects specific industrial control system modules with vulnerable firmware versions. The CVSS 9.8 score indicates critical severity.
💻 Affected Systems
- MELSEC iQ-R RJ71EIP91 EtherNet/IP Network Interface Module
- MELSEC iQ-R RJ71PN92 PROFINET IO Controller Module
- MELSEC iQ-R RD81DL96 High Speed Data Logger Module
- MELSEC iQ-R RD81MES96N MES Interface Module
- MELSEC iQ-R RD81OPC96 OPC UA Server Module
📦 What is this software?
Melsec Iq Rd81dl96 Firmware by Mitsubishielectric
Melsec Iq Rd81mes96n Firmware by Mitsubishielectric
Melsec Iq Rd81opc96 Firmware by Mitsubishielectric
Melsec Iq Rj71eip91 Firmware by Mitsubishielectric
Melsec Iq Rj71pn92 Firmware by Mitsubishielectric
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, disruption of industrial processes, and potential physical damage or safety incidents.
Likely Case
Denial of service causing network function stoppage and disruption of industrial operations.
If Mitigated
Limited impact if modules are isolated in protected networks with proper segmentation and monitoring.
🎯 Exploit Status
No public exploit code found in references, but vulnerability details are public and exploitation appears straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Updated firmware versions specified in vendor advisories
Vendor Advisory: https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-012_en.pdf
Restart Required: Yes
Instructions:
1. Identify affected modules using serial numbers. 2. Download updated firmware from Mitsubishi Electric support. 3. Follow vendor instructions to update firmware on each module. 4. Verify serial numbers are no longer in vulnerable ranges.
🔧 Temporary Workarounds
Network segmentation and isolation
allIsolate affected modules in separate network segments with strict firewall rules to prevent unauthorized access.
Access control restrictions
allImplement network access controls to limit which systems can communicate with vulnerable modules.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate vulnerable modules from untrusted networks.
- Deploy intrusion detection systems to monitor for anomalous network traffic targeting these modules.
🔍 How to Verify
Check if Vulnerable:
Check serial numbers on affected modules: RJ71EIP91 (first 2 digits '02' or before), RJ71PN92 (first 2 digits '01' or before), RD81DL96 (first 2 digits '08' or before), RD81MES96N (first 2 digits '04' or before), RD81OPC96 (first 2 digits '04' or before).Check Version:
Check module firmware version via Mitsubishi Electric configuration tools (specific commands vary by module).Verify Fix Applied:
Verify serial numbers are updated beyond vulnerable ranges after firmware update.📡 Detection & Monitoring
Log Indicators:
- Module crash logs
- Network function stoppage events
- Unexpected module restarts
Network Indicators:
- Unusual TCP/IP traffic patterns to module ports
- Crafted packets targeting module network services
SIEM Query:
Search for network traffic to industrial control modules with payload patterns matching buffer overflow attempts.🔗 References
- https://jvn.jp/vu/JVNVU92513419/index.html
- https://www.mitsubishielectric.co.jp/psirt/vulnerability/pdf/2020-012.pdf
- https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-012_en.pdf
- https://jvn.jp/vu/JVNVU92513419/index.html
- https://www.mitsubishielectric.co.jp/psirt/vulnerability/pdf/2020-012.pdf
- https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-012_en.pdf
