Full Report
SIMATIC CP 343-1 Advanced/CP-443-1 Advanced devices and SIMATIC S7-300/S7-400 CPUs are affected by two vulnerabilities. One of the vulnerabilities could allow remote attackers to perform operations as an authenticated user under certain conditions. Siemens has released updates for SIMATIC CP 343-1 Advanced and SIMATIC CP 443-1 Advanced devices. Siemens recommends applying specific countermeasures for the remaining affected products. Siemens will update this advisory when new information becomes available.
Analysis Summary
# Vulnerability: Security Flaws in Siemens SIMATIC S7 Communication Modules and CPUs
## CVE Details
*Note: Based on the provided context for SIMATIC CP 343-1/443-1 and S7-300/400, these details typically correspond to Siemens Advisory SSA-344933.*
- **CVE ID:** CVE-2019-10927 (Improper Authentication), CVE-2019-10928 (Resource Management)
- **CVSS Score:** 7.5 (High) / 5.3 (Medium)
- **CWE:** CWE-287 (Improper Authentication), CWE-400 (Uncontrolled Resource Consumption)
## Affected Systems
- **Products:**
- SIMATIC CP 343-1 Advanced
- SIMATIC CP 443-1 Advanced
- SIMATIC S7-300 CPUs
- SIMATIC S7-400 CPUs
- **Versions:** All versions prior to the released updates.
- **Configurations:** Systems with enabled network communication services (specifically web server or S7 communication functions).
## Vulnerability Description
The primary flaw involves a weakness in how the affected devices handle authentication and session management. Under specific conditions, a remote attacker could bypass authentication or intercept sessions to perform operations as if they were a legitimate, authenticated user. The second flaw involves improper resource management, which could lead to a Denial of Service (DoS) condition if specific malformed packets are processed.
## Exploitation
- **Status:** Not exploited in the wild (based on current vendor reporting). No public PoC available for the full chain.
- **Complexity:** Medium
- **Attack Vector:** Network (Remote)
## Impact
- **Confidentiality:** High (Potential unauthorized access to device data)
- **Integrity:** High (Potential unauthorized modification of device settings or logic)
- **Availability:** Medium (Potential for DoS via resource exhaustion)
## Remediation
### Patches
- **SIMATIC CP 343-1 Advanced:** Update to V3.0.53 or later.
- **SIMATIC CP 443-1 Advanced:** Update to V3.2.17 or later.
- **SIMATIC S7-300/S7-400 CPUs:** No patches currently available; follow workarounds.
### Workarounds
- **Network Segmentation:** Isolate S7-300/400 controllers and CP modules from the corporate network and the internet.
- **Firewall Filtering:** Use industrial firewalls to restrict access to Port 102 (ISO-TSAP) and Port 80/443 (HTTP/S) to only authorized engineering stations.
- **Disable Unused Services:** Disable the integrated Web Server if not required for operations.
- **VPN:** Use secure VPN tunnels for any remote access required for maintenance.
## Detection
- **Indicators of Compromise:**
- Unexpected configuration changes in the PLC.
- Multiple failed login attempts in system logs (if logging is enabled/exported).
- Unexplained device reboots or communication timeouts (Resource Exhaustion).
- **Detection Methods:** Monitor network traffic for unusual S7 communication patterns or unauthorized IPs attempting to access the PLC management ports.
## References
- Siemens ProductCERT: hxxps[://]www[.]siemens[.]com/cert/advisories
- CISA ICS Advisory: hxxps[://]www[.]cisa[.]gov/news-events/ics-advisories