Full Report
Siemens User Management Component (UMC) before V2.11.2 is affected by multiple vulnerabilities where the most severe could lead to a restart of the UMC server. Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where fixes are not, or not yet available.
Analysis Summary
# Vulnerability: Multiple Denial of Service Flaws in Siemens UMC
## CVE Details
- **CVE ID:** CVE-2023-46281, CVE-2023-46282, CVE-2023-46283, CVE-2023-46284, CVE-2023-46285
- **CVSS Score:** 7.5 (High)
- **CWE:** CWE-120 (Classic Buffer Overflow), CWE-20 (Improper Input Validation)
## Affected Systems
- **Products:** Siemens User Management Component (UMC) integrated within:
- Opcenter Execution Foundation
- Opcenter Quality
- SIMATIC PCS neo
- SINEC NMS
- TIA Portal (V14, V15.1, V16, V17, V18, V19)
- **Versions:** All versions of UMC before V2.11.2.
- **Configurations:** Systems where UMC services are listening on ports 4002/tcp and 4004/tcp.
## Vulnerability Description
The Siemens UMC is affected by multiple memory corruption and input validation vulnerabilities. Specifically, the application fails to properly validate the size of input buffers or the structure of incoming messages on ports 4002/tcp and 4004/tcp.
- **CVE-2023-46281 through CVE-2023-46284:** Represent Buffer Overflows (CWE-120) or Out-of-Bounds writes.
- **CVE-2023-46285:** Represents an Improper Input Validation flaw.
In all cases, a remote unauthenticated attacker can send specially crafted packets to trigger a crash of the UMC server. While the service typically auto-restarts via a watchdog, repeated exploitation results in a persistent Denial of Service (DoS) state.
## Exploitation
- **Status:** PoC available (indicated by 'E:P' in the CVSS vector).
- **Complexity:** Low
- **Attack Vector:** Network
## Impact
- **Confidentiality:** None
- **Integrity:** None
- **Availability:** High (The UMC server can be crashed repeatedly, disrupting authentication and user management services).
## Remediation
### Patches
Siemens recommends updating the host products to versions that include UMC V2.11.2 or later:
- **Opcenter Execution Foundation:** Update to V2407 or later.
- **Opcenter Quality:** Update to V2312 or later.
- **SIMATIC PCS neo:** Update to V4.1 or later.
- **SINEC NMS:** Update to V2.0 SP1 or later.
- **TIA Portal:** Update to V19 (Note: No fixes are planned for V14 and V16).
### Workarounds
- Limit access to ports 4002/tcp and 4004/tcp using firewalls or network segmentation to trusted internal traffic only.
- Implement the "Defense-in-Depth" concept as per Siemens' operational security guidelines.
## Detection
- **Indicators of Compromise:** Frequent, unexplained restarts of the UMC service or associated watchdog triggers.
- **Detection Methods:** Monitor network traffic for unusual or malformed payloads targeting ports 4002/tcp and 4004/tcp. Check system logs for "Buffer Overflow" or "Access Violation" errors related to UMC executable components.
## References
- **Vendor Advisory:** hxxps://cert-portal.siemens[.]com/productcert/pdf/ssa-999588.pdf
- **Siemens ProductCERT:** hxxps://www.siemens[.]com/cert/advisories
- **Patch Link (Opcenter):** hxxps://support.sw.siemens[.]com/product/219646572/
- **Patch Link (SINEC):** hxxps://support.industry.siemens[.]com/cs/ww/en/view/109826954/