CVE-2021-27442
📋 TL;DR
This cross-site scripting vulnerability in Weintek cMT products allows unauthenticated remote attackers to inject malicious JavaScript code into web interfaces. It affects industrial control systems using these human-machine interfaces, potentially compromising device integrity and operations.
💻 Affected Systems
- Weintek cMT product line with EasyWeb V1
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device takeover, credential theft, malware deployment, and lateral movement to other industrial systems.
Likely Case
Session hijacking, data theft, unauthorized configuration changes, and disruption of HMI operations.
If Mitigated
Limited impact with proper network segmentation, web application firewalls, and input validation controls.
🎯 Exploit Status
Standard XSS exploitation techniques apply; no authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware updates specified in Weintek TEC21001E advisory
Vendor Advisory: https://dl.weintek.com/public/Document/TEC/TEC21001E_cMT_EasyWeb_V1_Security_Issues.pdf
Restart Required: Yes
Instructions:
1. Download firmware update from Weintek website. 2. Backup current configuration. 3. Apply firmware update via USB or network. 4. Restart device. 5. Verify update applied successfully.
🔧 Temporary Workarounds
Network Segmentation
allIsolate cMT devices in separate VLAN with restricted access.
Web Application Firewall
allDeploy WAF with XSS protection rules in front of cMT devices.
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach cMT web interfaces.
- Disable unnecessary web interface features and use alternative management methods.
🔍 How to Verify
Check if Vulnerable:
Check firmware version against patched versions in vendor advisory; test with safe XSS payloads in controlled environment.Check Version:
Check device web interface system information page or use vendor-specific CLI commands.Verify Fix Applied:
Verify firmware version matches patched version; test that XSS payloads no longer execute.📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript in web requests
- Multiple failed login attempts after XSS payloads
- Configuration changes from unexpected sources
Network Indicators:
- HTTP requests containing script tags or JavaScript payloads to cMT devices
- Unusual outbound connections from cMT devices
SIEM Query:
source_ip="cMT_device" AND (http_uri CONTAINS "<script>" OR http_uri CONTAINS "javascript:")