Full Report
Siemens SINEC NMS when used with User Management Component (UMC) contains an authentication bypass vulnerability due to insufficient validation of user identity. This could allow an unauthenticated remote attacker to bypass authentication and gain unauthorized access to the application. Siemens has released a new version for SINEC NMS and recommends to update to the latest version.
Analysis Summary
# Vulnerability: Authentication Bypass in Siemens SINEC NMS
## CVE Details
- **CVE ID:** CVE-2026-24032
- **CVSS Score:**
- **v3.1:** 7.3 (High)
- **v4.0:** 6.9 (Medium)
- **CWE:** CWE-347: Improper Verification of Cryptographic Signature
## Affected Systems
- **Products:** Siemens SINEC NMS (Network Management System)
- **Versions:** All versions prior to V4.0 SP3
- **Configurations:** Systems configured to use the User Management Component (UMC) for authentication.
## Vulnerability Description
The vulnerability exists within the User Management Component (UMC) integrated with SINEC NMS. Due to improper verification of cryptographic signatures (CWE-347) and insufficient validation of user identity, the system fails to correctly authenticate users. A remote attacker can exploit this flaw to bypass the authentication mechanism, granting them unauthorized access to the network management platform.
## Exploitation
- **Status:** Not currently reported as exploited in the wild; coordinated disclosure via Trend Micro Zero Day Initiative (ZDI-CAN-27564).
- **Complexity:** Low
- **Attack Vector:** Network (Remote)
## Impact
- **Confidentiality:** Low (Unauthorized access to system information)
- **Integrity:** Low (Potential for unauthorized configuration changes)
- **Availability:** Low (Potential for service disruption via unauthorized access)
## Remediation
### Patches
- Siemens recommends updating SINEC NMS to **V4.0 SP3 or later**.
- Software Update Link: hxxps[://]support[.]industry[.]siemens[.]com/cs/ww/en/view/110000760/
### Workarounds
- **Network Segmentation:** Protect network access to the SINEC NMS instance using firewalls and VLANs to ensure only trusted traffic can reach the UMC component.
- **Operational Guidelines:** Adhere to Siemens’ operational guidelines for Industrial Security, which include isolating industrial networks from the enterprise IT network.
## Detection
- **Indicators of Compromise:** Unusual login patterns or administrative actions appearing from unknown or unexpected IP addresses.
- **Detection methods and tools:**
- Monitor UMC and SINEC NMS audit logs for successful logins that do not correlate with known authorized personnel.
- Utilize Intrusion Detection Systems (IDS) to monitor traffic directed at the UMC authentication endpoints.
## References
- **Siemens Security Advisory SSA-801704:** hxxps[://]cert-portal[.]siemens[.]com/productcert/html/ssa-801704[.]html
- **Siemens Industrial Security Home:** hxxps[://]www[.]siemens[.]com/industrialsecurity
- **Contact Siemens ProductCERT:** hxxps[://]www[.]siemens[.]com/cert/advisories