OTPulse

Siemens SIMATIC S7-1200 CPU Web Vulnerabilities

Act NowICS-CERT ICSA-14-114-02Jan 25, 2014
Siemens
Summary

Siemens SIMATIC S7-1200 CPU web interface contains cross-site scripting (XSS) and HTTP response splitting vulnerabilities (CWE-79, CWE-113). These flaws allow an attacker to inject malicious scripts or craft HTTP headers without proper validation. An attacker with network access to the web interface could execute arbitrary JavaScript in the context of legitimate users, potentially leading to session hijacking, parameter manipulation, or unauthorized commands sent to the controller. The vulnerabilities affect S7-1200 CPU firmware versions 2.X and 3.X, and no patch is currently available from Siemens.

What this means
What could happen
An attacker with network access to the web interface of an S7-1200 CPU could inject malicious scripts or craft HTTP requests that manipulate process parameters, potentially disrupting production operations or enabling command execution on the controller.
Who's at risk
Operators of water treatment plants, wastewater systems, power distribution substations, and manufacturing facilities using Siemens S7-1200 PLCs as process controllers. This affects any site where the S7-1200 CPU web interface is exposed to internal networks or accessible remotely for monitoring or configuration.
How it could be exploited
An attacker sends crafted HTTP requests or injects JavaScript into the web interface of the S7-1200 CPU. The application does not properly validate or filter user input, allowing the injected content to be executed in the browser of an engineering technician or reflected in the HTTP response. This could allow theft of session tokens, modification of I/O setpoints, or further compromise of the control system.
Prerequisites
  • Network access to the S7-1200 CPU web interface (typically port 80/443)
  • No authentication required to exploit web injection vulnerabilities
Remotely exploitable via web interfaceNo authentication requiredLow attack complexity (simple HTTP request or HTML injection)No patch available from vendorModerate exploit probability (38.7% EPSS)
Exploitability
Likely to be exploited — EPSS score 68.0%
Affected products (1)
ProductAffected VersionsFix Status
SIMATIC S7-1200 CPU family: 2.X|3.X2.X|3.XNo fix yet
Remediation & Mitigation
0/5
Do now
0/3
HARDENINGImplement network segmentation to isolate the S7-1200 CPU from untrusted networks. Restrict HTTP/HTTPS access to the web interface to only authorized engineering workstations using firewall rules or access control lists.
WORKAROUNDDisable the web interface entirely if it is not actively used for monitoring or configuration. Access the CPU via Siemens engineering tools (TIA Portal) over a secured, air-gapped management network instead.
HARDENINGIf the web interface must remain enabled, implement a reverse proxy or WAF (Web Application Firewall) in front of the S7-1200 to filter malicious HTTP requests and block script injection attempts.
Schedule — requires maintenance window
0/1

Patching may require device reboot — plan for process interruption

HARDENINGMonitor HTTP access logs and alert on suspicious requests (e.g., with special characters, script tags, or unusual parameter values) targeting the CPU web interface.
Long-term hardening
0/1
HARDENINGPlan migration to newer Siemens S7-1200 firmware or successor platforms (S7-1500) that address these web security issues, as no patch is available for the current firmware versions.
View full CISA ICS-CERT advisory
API: /api/v1/advisories/31d35a0a-997e-42ed-af8b-d1978015ba43

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Siemens SIMATIC S7-1200 CPU Web Vulnerabilities - OTPulse