CVE-2020-7566
📋 TL;DR
This vulnerability allows attackers to break encryption keys used between EcoStruxure Machine - Basic software and Modicon M221 controllers by capturing network traffic. The weak random value generation makes cryptographic keys predictable. All Modicon M221 PLC users with these communication channels are affected.
💻 Affected Systems
- Modicon M221 Programmable Logic Controller
📦 What is this software?
Modicon M221 Firmware by Schneider Electric
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of industrial control system communications, allowing attackers to intercept, modify, or inject commands to PLCs, potentially causing physical damage or production disruption.
Likely Case
Unauthorized access to industrial control communications, enabling monitoring of sensitive industrial processes and potential manipulation of PLC operations.
If Mitigated
Limited impact with proper network segmentation and monitoring, though encryption remains vulnerable if traffic is captured.
🎯 Exploit Status
Exploitation requires network traffic capture capability and cryptographic analysis skills. No public exploit code has been released.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 1.10.3.0 or later
Vendor Advisory: https://www.se.com/ww/en/download/document/SEVD-2020-315-05/
Restart Required: Yes
Instructions:
1. Download firmware update from Schneider Electric website. 2. Connect to M221 controller via EcoStruxure Machine - Basic software. 3. Upload new firmware to controller. 4. Restart controller to apply update.
🔧 Temporary Workarounds
Network Segmentation
allIsolate Modicon M221 controllers and engineering workstations on separate VLANs with strict access controls
Encrypted Tunnel
allUse VPN or other encrypted tunnel for communication between engineering software and PLCs
🧯 If You Can't Patch
- Implement strict network segmentation to isolate PLC traffic from general network
- Deploy network monitoring to detect unusual traffic patterns between engineering stations and PLCs
🔍 How to Verify
Check if Vulnerable:
Check firmware version on Modicon M221 controller via EcoStruxure Machine - Basic software. Versions below 1.10.3.0 are vulnerable.Check Version:
Not applicable - version check performed through EcoStruxure Machine - Basic software interfaceVerify Fix Applied:
Confirm firmware version is 1.10.3.0 or later in controller properties via EcoStruxure Machine - Basic software.📡 Detection & Monitoring
Log Indicators:
- Unusual connection attempts to Modicon M221 controllers
- Multiple failed authentication attempts to engineering software
Network Indicators:
- Unusual traffic patterns between engineering workstations and PLCs
- Network sniffing tools detected on control network
SIEM Query:
source_ip="engineering_workstation" AND dest_ip="plc_network" AND protocol="modbus_tcp" AND bytes_transferred>threshold