Full Report
A vulnerability has been identified in the SIMATIC S7-1500 CPU family and related products that could allow an attacker to cause a denial of service condition. In order to exploit the vulnerability, an attacker must have access to the affected devices on port 102/tcp. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens is preparing further updates and recommends specific countermeasures for products where updates are not, or not yet available.
Analysis Summary
# Vulnerability: Denial of Service in SIMATIC S7-1500 CPU Family (CVE-2023-46156)
## CVE Details
- CVE ID: CVE-2023-46156
- CVSS Score: 7.5 (High)
- CWE: CWE-416: Use After Free
## Affected Systems
- Products: SIMATIC S7-1500 CPU family and related products, including SIMATIC Drive Controller CPUs, SIMATIC ET 200SP Open Controller CPU 1515SP PC2, and specific SIMATIC S7-1500 CPUs (Safety & Standard). SIPLUS variants are also noted as being affected if based on vulnerable firmware.
- Versions: Varies significantly by specific CPU model. Check the vendor advisory for precise details. Examples include all versions < V3.1.0 for CPU 1504D TF, and all versions for certain F-PN and non-DP models where no fix is currently planned.
- Configurations: Exploitation requires network access to the affected devices on TCP port 102.
## Vulnerability Description
The vulnerability (CVE-2023-46156) resides in how affected Siemens devices improperly handle specially crafted network packets sent to the Siemens proprietary communication port 102/tcp. Successful exploitation allows an unauthenticated, remote attacker to trigger a Denial of Service (DoS) condition, requiring a manual restart of the device to restore normal operation. The underlying weakness is identified as a Use After Free (CWE-416).
## Exploitation
- Status: PoC available (Implied by the advisory structure and common disclosure practice, though not explicitly stated as public, based on the high severity and available vector). The advisory indicates exploitation is feasible (E:P for Exploitability Maturity).
- Complexity: Low (AC:L - Attack Complexity Low)
- Attack Vector: Network (AV:N)
## Impact
- Confidentiality: No impact (C:N)
- Integrity: No impact (I:N)
- Availability: High impact (A:H - Results in Denial of Service requiring a restart)
## Remediation
### Patches
Siemens has released updates for numerous affected products. Users must upgrade to the specified minimum versions:
- **SIMATIC Drive Controller CPU 1504D TF / 1507D TF:** Update to V3.1.0 or later.
- **SIMATIC ET 200SP Open Controller CPU 1515SP PC2:** Update to V30.1.0 or later.
- **SIMATIC S7-1500 CPU 1510SP-1 PN (6ES7510-1SK03-0AB0):** Update to V3.1.0 or later.
- **Other CPUs (e.g., specific F-PN models):** Refer to the advisory for specific patch versions corresponding to CVE-2023-46156.
*Note: For several specific CPU models, Siemens currently states that **no fix is planned** at the time of V1.2 publication, emphasizing the need for workarounds.*
### Workarounds
For devices where an update is not yet available or not planned:
1. **Network Segmentation:** Implement strict network segmentation to isolate the affected PLCs from unauthorized access.
2. **Port Restriction:** Restrict access to TCP port 102 to only trusted network segments or maintenance hosts via firewall rules.
## Detection
- Indicators of Compromise: Sudden, unexpected device resets or restarts where the cause is not apparent from standard operational logs.
- Detection methods and tools: Network monitoring tools capable of inspecting traffic patterns on port 102/tcp for malformed frames or protocols. Review device logs for unexpected shutdowns followed by initialization sequences.
## References
- Vendor Advisories: [https://cert-portal.siemens.com/productcert/html/ssa-592380.html](https://cert-portal.siemens.com/productcert/html/ssa-592380.html)
- Siemens Product Support Link (for general firmware updates): [https://support.industry.siemens.com/cs/ww/en/view/109773914/](https://support.industry.siemens.com/cs/ww/en/view/109773914/)