Analysis Summary
Based on the Siemens ProductCERT SSB-091449 advisory, here is the summarized vulnerability information regarding SIMATIC S7 controllers.
# Vulnerability: Authentication Bypass and Improper Protection of Communication in SIMATIC S7-1500 and S7-1200
## CVE Details
- **CVE ID:** CVE-2022-38773
- **CVSS Score:** 7.5 (High)
- **CWE:** CWE-306 (Missing Authentication for Critical Function)
## Affected Systems
- **Products:**
- SIMATIC S7-1200 CPU family
- SIMATIC S7-1500 CPU family (including ET 200SP, ET 200pro, Drive Controller, and Software Controllers)
- **Versions:**
- S7-1200: All versions prior to v4.6.0
- S7-1500: All versions prior to v3.0.0
- **Configurations:** Systems using the "legacy" communication protocols or ODK (Open Development Kit) applications that do not utilize the newer "Secure Communication" features.
## Vulnerability Description
The vulnerability stems from the way older firmware versions handle the proprietary S7 communication protocol. An attacker can bypass the password protection for CPU access levels (Read, Write, or Full access) by intercepting and replaying specific communication sequences or by exploiting flaws in the authentication handshake. This allows unauthorized users to perform administrative tasks, modify PLC logic, or extract sensitive data without the correct credentials.
## Exploitation
- **Status:** PoC available (Techniques have been demonstrated by researchers, specifically regarding the "LLDH" handshake).
- **Complexity:** Medium
- **Attack Vector:** Network (The attacker must have network access to the PLC’s communication port, typically TCP/102).
## Impact
- **Confidentiality:** High (Unauthorized reading of program code and process data).
- **Integrity:** High (Unauthorized modification of PLC logic and variables).
- **Availability:** High (Potential to stop the CPU or cause process disruption).
## Remediation
### Patches
Siemens has released firmware updates to address this vulnerability by introducing enhanced "Secure Communication" based on TLS.
- **SIMATIC S7-1200:** Update to **v4.6.0** or later.
- **SIMATIC S7-1500:** Update to **v3.0.0** or later.
### Workarounds
- **Enable Secure Communication:** Configure the PLC to use "Only allow secure PG/PC and HMI communication" in TIA Portal (requires v17 or higher).
- **Network Segmentation:** Isolate the ICS/OT network from the corporate network and ensure no direct internet exposure.
- **VPN usage:** Use encrypted VPN tunnels for any remote engineering access.
- **Physical Security:** Protect physical access to the PLC and the local network infrastructure.
## Detection
- **Indicators of Compromise:** Unusual engineering station connections originating from unexpected IP addresses; unauthorized "Stop" or "Download" commands logged in the CPU diagnostic buffer.
- **Detection Methods:**
- Use Industrial Intrusion Detection Systems (IDS) to monitor for non-standard S7 protocol handshakes.
- Monitor TCP port 102 for anomalous traffic patterns.
## References
- **Vendor Advisory:** hxxps[://]cert-portal[.]siemens[.]com/productcert/pdf/ssa-091449[.]pdf
- **Siemens Security Home:** hxxps[://]www[.]siemens[.]com/cert
- **CISA Advisory:** hxxps[://]www[.]cisa[.]gov/news-events/ics-advisories/icsa-22-286-01