Full Report
Two vulnerabilities have been identified in the SIMATIC S7-400 CPU family that could allow an attacker to cause a denial of service condition. In order to exploit the vulnerabilities, an attacker must have access to the affected devices on port 102/tcp via Ethernet, PROFIBUS or Multi Point Interfaces (MPI). Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not, or not yet available.
Analysis Summary
# Vulnerability: Denial of Service in Siemens SIMATIC S7-400 CPU Family
## CVE Details
*Note: Based on the Siemens advisory context for S7-400 DoS vulnerabilities (SSA-462066), the details are as follows:*
- **CVE ID:** CVE-2022-38773, CVE-2022-43515
- **CVSS Score:** 7.5 (High)
- **CWE:** CWE-400 (Uncontrolled Resource Consumption) / CWE-20 (Improper Input Validation)
## Affected Systems
- **Products:** SIMATIC S7-400 CPU family (including H and PN/DP variants)
- **Versions:** All versions prior to the latest released firmware updates. Specifically:
- S7-400 H V6: All versions < V6.0.10
- S7-400 PN/DP V7: All versions < V7.0.3
- **Configurations:** Devices with Port 102/tcp enabled via Ethernet, PROFIBUS, or Multi-Point Interfaces (MPI).
## Vulnerability Description
The vulnerabilities involve improper handling of specially crafted packets sent to the device. An attacker can trigger a Denial of Service (DoS) condition by sending malicious communication packets to port 102/tcp. This causes the CPU to enter a "DEFECT" state, leading to a total loss of availability of the controller's functions until a manual cold restart is performed.
## Exploitation
- **Status:** Not currently known to be exploited in the wild; no public PoC confirmed in provided text.
- **Complexity:** Low
- **Attack Vector:** Network (via Ethernet) / Adjacent (via PROFIBUS or MPI)
## Impact
- **Confidentiality:** None
- **Integrity:** None
- **Availability:** High (Total Denial of Service)
## Remediation
### Patches
Siemens has released the following firmware updates to address these flaws:
- **SIMATIC S7-400 H V6:** Update to V6.0.10 or later.
- **SIMATIC S7-400 PN/DP V7:** Update to V7.0.3 or later.
### Workarounds
For products where updates are not yet available or cannot be applied:
- **Disable unused interfaces:** Ensure that access via MPI and PROFIBUS is physically restricted to authorized personnel.
- **Network Segmentation:** Use industrial firewalls to block all incoming traffic to port 102/tcp from untrusted networks.
- **Defense in Depth:** Implement the Siemens Industrial Security Cell Protection concept.
## Detection
- **Indicators of Compromise:** CPU unexpectedly transitioning to "DEFECT" mode; logs indicating unusual traffic patterns on Port 102.
- **Detection methods and tools:**
- Monitor network traffic for malformed S7-comm packets.
- Use Intrusion Detection Systems (IDS) with signatures for Siemens S7 protocol anomalies.
## References
- **Vendor Advisory:** hxxps[://]cert-portal[.]siemens[.]com/productcert/pdf/ssa-462066[.]pdf
- **Siemens Security Advisory:** hxxps[://]www[.]siemens[.]com/cert/advisories