CVE-2021-21911
📋 TL;DR
This vulnerability allows local attackers to escalate privileges to SYSTEM authority on Windows systems running Advantech R-SeeNet 2.4.15 by replacing system files with malicious ones. It affects organizations using this specific version of the industrial monitoring software for unauthorized privilege elevation.
💻 Affected Systems
- Advantech R-SeeNet
📦 What is this software?
R Seenet by Advantech
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, enabling installation of persistent malware, credential theft, and lateral movement across the network.
Likely Case
Local privilege escalation allowing attackers to bypass security controls, install additional malware, and maintain persistence on compromised systems.
If Mitigated
Limited impact with proper file integrity monitoring, least privilege principles, and network segmentation in place.
🎯 Exploit Status
Exploitation requires local access but is straightforward once access is obtained. The vulnerability is well-documented in public advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to version newer than 2.4.15 (30.07.2021)
Vendor Advisory: https://www.advantech.com/support
Restart Required: Yes
Instructions:
1. Download latest R-SeeNet version from Advantech support portal. 2. Backup current configuration. 3. Run installer with administrative privileges. 4. Restart system after installation completes.
🔧 Temporary Workarounds
File Integrity Monitoring
windowsImplement monitoring for unauthorized file modifications in R-SeeNet installation directory
# Use Windows File Server Resource Manager or third-party FIM tools
# Configure alerts for changes to %PROGRAMFILES%\Advantech\R-SeeNet\
Restrict File Permissions
windowsRemove write permissions for non-administrative users on R-SeeNet installation directory
icacls "%PROGRAMFILES%\Advantech\R-SeeNet\" /deny Users:(OI)(CI)W
icacls "%PROGRAMFILES%\Advantech\R-SeeNet\" /deny Authenticated Users:(OI)(CI)W
🧯 If You Can't Patch
- Implement strict access controls to limit who can log into systems running R-SeeNet
- Deploy application whitelisting to prevent execution of unauthorized binaries
🔍 How to Verify
Check if Vulnerable:
Check R-SeeNet version in About dialog or installation directory properties. If version is 2.4.15 with date 30.07.2021, system is vulnerable.Check Version:
Check file properties of RSeeNet.exe in installation directory or view version in application interfaceVerify Fix Applied:
Verify R-SeeNet version is newer than 2.4.15 and check file integrity of installation directory.📡 Detection & Monitoring
Log Indicators:
- Windows Security logs showing file permission changes in R-SeeNet directory
- Application logs showing unexpected R-SeeNet service restarts
Network Indicators:
- Unusual outbound connections from R-SeeNet service account
- SMB traffic to R-SeeNet installation directory from unauthorized systems
SIEM Query:
source="Windows Security" EventCode=4663 ObjectName="*Advantech*R-SeeNet*" AccessMask="0x2"