CVE-2021-27446
📋 TL;DR
CVE-2021-27446 is a critical code injection vulnerability in Weintek cMT industrial HMI products that allows unauthenticated remote attackers to execute arbitrary commands with root privileges. This affects the cMT product line's EasyWeb interface, potentially compromising industrial control systems. Organizations using vulnerable Weintek cMT devices are at risk.
💻 Affected Systems
- Weintek cMT Series HMI devices
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary commands as root, potentially disrupting industrial operations, stealing sensitive data, or establishing persistent access to industrial control networks.
Likely Case
Remote code execution leading to unauthorized access, data exfiltration, or disruption of HMI functionality in industrial environments.
If Mitigated
Limited impact if devices are properly segmented, have network access controls, and are monitored for suspicious activity.
🎯 Exploit Status
Public exploit code exists and has been weaponized in attacks against industrial control systems.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: cMT EasyWeb V1 firmware dated 2021-03-18 or later
Vendor Advisory: https://dl.weintek.com/public/Document/TEC/TEC21001E_cMT_EasyWeb_V1_Security_Issues.pdf
Restart Required: Yes
Instructions:
1. Download the updated firmware from Weintek's official website. 2. Backup current configuration. 3. Apply firmware update via USB or network. 4. Restart the device. 5. Verify firmware version.
🔧 Temporary Workarounds
Network Segmentation
allIsolate cMT devices in separate network segments with strict firewall rules.
Disable EasyWeb V1
allDisable the vulnerable EasyWeb V1 interface if not required for operations.
🧯 If You Can't Patch
- Implement strict network access controls to limit access to cMT devices only from authorized IP addresses
- Monitor network traffic to/from cMT devices for suspicious activity and implement intrusion detection
🔍 How to Verify
Check if Vulnerable:
Check firmware version in device web interface or configuration utility; versions prior to 2021-03-18 are vulnerable.Check Version:
Check via device web interface at http://[device-ip]/config or using Weintek configuration toolsVerify Fix Applied:
Verify firmware version shows 2021-03-18 or later date in device configuration.📡 Detection & Monitoring
Log Indicators:
- Unusual command execution logs
- Unauthorized access attempts to EasyWeb interface
- Unexpected system modifications
Network Indicators:
- HTTP requests to cMT EasyWeb endpoints with suspicious parameters
- Unexpected outbound connections from cMT devices
SIEM Query:
source="cMT-device" AND (http_uri CONTAINS "/EasyWeb/" OR process="unusual_command")