Full Report
SINUMERIK ONE and SINUMERIK MC products are affected by a denial of service vulnerability in the OPC UA implementation of the integrated S7-1500 CPU. The vulnerability in the integrated S7-1500 CPU is documented in more detail in SSA-711309 [1]. Siemens has released updates for the affected products and recommends to update to the latest versions. [1] https://cert-portal.siemens.com/productcert/html/ssa-711309.html
Analysis Summary
# Vulnerability: Denial of Service in SINUMERIK OPC UA Implementation
## CVE Details
- **CVE ID:** CVE-2023-28831
- **CVSS Score:** 7.5 (High)
- **CWE:** CWE-190 (Integer Overflow or Wraparound)
## Affected Systems
- **Products:**
- SINUMERIK MC (CNC system for customized machine solutions)
- SINUMERIK ONE (Digital-native CNC system with integrated S7-1500 CPU)
- **Versions:**
- SINUMERIK MC: All versions < V1.22
- SINUMERIK ONE: All versions < V6.22
- **Configurations:** Systems utilizing the integrated S7-1500 CPU's OPC UA interface.
## Vulnerability Description
The OPC UA implementations (ANSI C and C++) used within the integrated S7-1500 CPU of affected SINUMERIK products contain an integer overflow vulnerability. This flaw occurs during the certificate validation process. Specifically, if a specially crafted certificate is processed, it can trigger an infinite loop within the application, leading to a complete Denial of Service (DoS) of the OPC UA functionality.
## Exploitation
- **Status:** PoC available (Exploit Code Maturity: Functional)
- **Complexity:** Low
- **Attack Vector:** Network (Remote)
## Impact
- **Confidentiality:** None
- **Integrity:** None
- **Availability:** High (The application becomes unresponsive due to an infinite loop)
## Remediation
### Patches
Siemens recommends updating affected products to the following versions or later:
- **SINUMERIK MC:** Update to V1.22 or later.
- **SINUMERIK ONE:** Update to V6.22 or later.
### Workarounds
- **Network Segmentation:** Expose the OPC UA interface of the integrated S7-1500 CPU only to trusted network environments.
- **General Defense:** Protect network access to devices with appropriate mechanisms (firewalls, VLANs) and follow Siemens' operational guidelines for Industrial Security.
## Detection
- **Indicators of Compromise:** Sudden unresponsiveness of the OPC UA interface or CPU stabilization issues during the establishment of encrypted connections.
- **Detection methods:** Monitor for unusual network traffic targeting the OPC UA port (typically TCP/4840) containing malformed security certificates or repeated failed handshake attempts.
## References
- **Vendor Advisories:**
- hxxps://cert-portal[.]siemens[.]com/productcert/html/ssa-118850.html
- hxxps://cert-portal[.]siemens[.]com/productcert/html/ssa-711309.html
- **Support Links:**
- hxxps://support[.]industry[.]siemens[.]com/cs/ww/en/view/109824227/
- hxxps://www[.]siemens[.]com/cert/operational-guidelines-industrial-security