Siemens SIMATIC S7-1200 CPU Protection Mechanism Failure
Monitor6.5ICS-CERT ICSA-16-075-01Dec 17, 2016
Attack VectorNetwork
Auth RequiredNone
ComplexityLow
User InteractionNone needed
Summary
SIMATIC S7-1200 CPUs prior to firmware version 4.0 fail to properly enforce authentication on the S7 communication protocol (Profibus/Profinet). An unauthenticated attacker with network access can read and write CPU memory, upload malicious program code, and modify process data without presenting valid engineering credentials. This breaks the confidentiality and integrity of the control system.
What this means
What could happen
An attacker with network access to the PLC can read and modify program logic and data memory without authentication, potentially altering process control setpoints, disabling safety interlocks, or corrupting data integrity.
Who's at risk
Water treatment and distribution facilities, municipal electric utilities, and other critical infrastructure that rely on Siemens S7-1200 PLCs for pump station control, valve actuation, or load balancing. The S7-1200 is widely deployed in small- to mid-size control systems.
How it could be exploited
An attacker sends Profibus/Profinet requests to port 102 to access the S7 communication protocol. Because the CPU lacks proper authentication enforcement, the attacker can read CPU memory and upload modified program code to the PLC without valid engineering credentials.
Prerequisites
- Network access to port 102 (S7 protocol)
- SIMATIC S7-1200 CPU running firmware version 4.0 or earlier
- No authentication or firewall segmentation in place
remotely exploitableno authentication requiredlow complexityno patch availableaffects safety systems
Exploitability
Low exploit probability (EPSS 0.2%)
Affected products (1)
ProductAffected VersionsFix Status
SIMATIC S7-1200 CPU family: <V4.0<V4.0No fix (EOL)
Remediation & Mitigation
0/4
Do now
0/2HARDENINGIsolate SIMATIC S7-1200 CPUs from untrusted networks using firewall rules or air-gapping. Restrict access to port 102 to only authorized engineering workstations.
WORKAROUNDDisable remote access to the S7 communication port on the CPU if not required for normal operations.
Mitigations - no patch available
0/2SIMATIC S7-1200 CPU family: <V4.0 has reached End of Life. The vendor will not release a patch. Apply the following compensating controls:
HARDENINGImplement network segmentation to place S7-1200 CPUs in a restricted OT zone with limited connectivity to IT networks and untrusted systems.
HARDENINGMonitor S7 protocol traffic to the CPU for unauthorized access attempts or unusual commands.
CVEs (1)
↑↓ Navigate · Esc Close
API:
/api/v1/advisories/9e9d43a3-b1d4-4bc5-a50e-5119c2a7292b