CVE-2025-66266
📋 TL;DR
CVE-2025-66266 is a local privilege escalation vulnerability in UPSilon 2000's RupsMon.exe service. The service executable has insecure permissions granting 'Everyone' group Full Control, allowing local attackers to replace it with malicious code that runs with SYSTEM privileges. This affects systems running UPSilon 2000 software.
💻 Affected Systems
- UPSilon 2000
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, enabling attacker persistence, data theft, lateral movement, and disabling of security controls.
Likely Case
Local privilege escalation from standard user to SYSTEM, allowing installation of malware, credential harvesting, and bypassing security software.
If Mitigated
Limited impact if proper access controls and monitoring are in place, though privilege escalation risk remains if initial access is gained.
🎯 Exploit Status
Exploitation requires local access but is straightforward - involves replacing the executable or modifying service configuration. No authentication bypass needed beyond local system access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.megatec.com.tw/software-download/
Restart Required: Yes
Instructions:
1. Check vendor website for security updates. 2. Download and install any available patches. 3. Restart affected systems. 4. Verify RupsMon.exe permissions are corrected.
🔧 Temporary Workarounds
Secure RupsMon.exe Permissions
windowsRemove 'Everyone' group Full Control permissions from RupsMon.exe and restrict to necessary users/groups.
icacls "C:\Path\To\RupsMon.exe" /remove Everyone
icacls "C:\Path\To\RupsMon.exe" /grant SYSTEM:F
icacls "C:\Path\To\RupsMon.exe" /grant "Administrators":F
Disable UPSilon Service
windowsTemporarily disable the UPSilon service if not critically needed.
sc stop UPSilonService
sc config UPSilonService start= disabled
🧯 If You Can't Patch
- Implement strict access controls to limit who can log into affected systems.
- Deploy application whitelisting to prevent unauthorized executable modifications.
- Monitor for unauthorized service configuration changes and file modifications to RupsMon.exe.
🔍 How to Verify
Check if Vulnerable:
Check RupsMon.exe permissions: icacls "C:\Path\To\RupsMon.exe" and look for 'Everyone:(F)' or similar excessive permissions.Check Version:
Check UPSilon 2000 version through installed programs or vendor documentation.Verify Fix Applied:
Verify RupsMon.exe permissions no longer include 'Everyone' group with Full Control: icacls "C:\Path\To\RupsMon.exe" | findstr Everyone📡 Detection & Monitoring
Log Indicators:
- Windows Security Event ID 4663 (File system modification) for RupsMon.exe
- Service Control Manager events for UPSilon service stops/starts
- Unexpected process creation from RupsMon.exe location
Network Indicators:
- None - this is a local privilege escalation vulnerability
SIEM Query:
EventID=4663 AND ObjectName="*RupsMon.exe" OR (EventID=7036 AND ServiceName="UPSilon*")