CVE-2021-27486
📋 TL;DR
CVE-2021-27486 is an integer underflow vulnerability in FATEK Automation WinProladder PLC programming software that can lead to out-of-bounds writes and arbitrary code execution. Attackers could exploit this to take control of affected systems. Organizations using WinProladder versions 3.30 and earlier for industrial control system programming are affected.
💻 Affected Systems
- FATEK Automation WinProladder
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary code, potentially disrupting industrial processes, stealing sensitive data, or establishing persistent access to control systems.
Likely Case
Local privilege escalation or remote code execution when malicious project files are opened, potentially leading to lateral movement within industrial networks.
If Mitigated
Limited impact if systems are isolated, use application whitelisting, and restrict user privileges, though the vulnerability remains present.
🎯 Exploit Status
Exploitation requires user interaction to open malicious project files. No public exploit code has been released.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 3.31 or later
Vendor Advisory: https://us-cert.cisa.gov/ics/advisories/icsa-21-098-01
Restart Required: No
Instructions:
1. Download WinProladder version 3.31 or later from FATEK Automation website. 2. Uninstall previous version. 3. Install updated version. 4. Verify installation by checking Help > About for version number.
🔧 Temporary Workarounds
Restrict project file sources
windowsOnly open project files from trusted sources and implement file validation procedures.
Application control policies
windowsImplement application whitelisting to restrict execution of unauthorized software.
🧯 If You Can't Patch
- Isolate WinProladder systems from production networks and internet access
- Implement strict user privilege controls and disable unnecessary features
🔍 How to Verify
Check if Vulnerable:
Open WinProladder, go to Help > About, check if version is 3.30 or earlier.Check Version:
Not applicable - check via GUI Help > About menuVerify Fix Applied:
After updating, verify version is 3.31 or later in Help > About dialog.📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes
- Suspicious file access patterns
- Unusual process creation from WinProladder
Network Indicators:
- Unexpected network connections from WinProladder process
- File transfers to/from engineering workstations
SIEM Query:
Process:WinProladder.exe AND (EventID:1000 OR EventID:1001) OR FileAccess:*.prl