CVE-2026-25655
📋 TL;DR
A vulnerability in SINEC NMS allows low-privileged users to modify configuration files, enabling DLL hijacking attacks. This could lead to arbitrary code execution with administrative privileges. All SINEC NMS versions before V4.0 SP2 are affected.
💻 Affected Systems
- SINEC NMS
📦 What is this software?
Sinec Nms by Siemens
Sinec Nms by Siemens
Sinec Nms by Siemens
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with administrative privileges, allowing complete control over the SINEC NMS server and potential lateral movement within the network.
Likely Case
Privilege escalation leading to administrative control of the SINEC NMS application, enabling configuration manipulation, data exfiltration, or persistence mechanisms.
If Mitigated
Limited impact with proper access controls and monitoring, potentially only allowing configuration changes without code execution.
🎯 Exploit Status
Exploitation requires authenticated low-privileged access and ability to place malicious DLLs. The vulnerability is documented in ZDI-CAN-28107.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: V4.0 SP2 or later
Vendor Advisory: https://cert-portal.siemens.com/productcert/html/ssa-311973.html
Restart Required: Yes
Instructions:
1. Download SINEC NMS V4.0 SP2 or later from Siemens support portal. 2. Backup current configuration and data. 3. Install the update following Siemens installation guide. 4. Restart the SINEC NMS service or server.
🔧 Temporary Workarounds
Restrict file permissions
windowsApply strict file system permissions to prevent low-privileged users from writing to SINEC NMS configuration directories.
icacls "C:\Program Files\Siemens\SINEC NMS\" /inheritance:r /grant:r "Administrators:(OI)(CI)F" /grant:r "SYSTEM:(OI)(CI)F"
Implement DLL protection
windowsUse Windows security features like SafeDllSearchMode and CWDIllegalInDllSearch to prevent DLL hijacking.
reg add "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager" /v SafeDllSearchMode /t REG_DWORD /d 1 /f
reg add "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager" /v CWDIllegalInDllSearch /t REG_DWORD /d 0x400 /f
🧯 If You Can't Patch
- Implement strict access controls to limit low-privileged user access to SINEC NMS systems
- Monitor file system changes in SINEC NMS directories and DLL loading events
🔍 How to Verify
Check if Vulnerable:
Check SINEC NMS version in application interface or installation directory. Versions below V4.0 SP2 are vulnerable.Check Version:
Check SINEC NMS web interface or examine installation directory propertiesVerify Fix Applied:
Verify SINEC NMS version shows V4.0 SP2 or later. Test that low-privileged users cannot modify configuration files.📡 Detection & Monitoring
Log Indicators:
- Unauthorized file modifications in SINEC NMS directories
- Unexpected DLL loading events from SINEC NMS process
- Failed permission attempts on configuration files
Network Indicators:
- Unusual outbound connections from SINEC NMS server
- Suspicious authentication patterns to SINEC NMS
SIEM Query:
source="windows-security" EventCode=4663 ObjectName="*SINEC NMS*" AccessMask="0x2" | stats count by AccountName, ObjectName