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             AUSCERT External Security Bulletin Redistribution

  Advisory (ICSA-14-226-01) Siemens SIMATIC S7-1500 CPU Denial of Service
                              18 August 2014


        AusCERT Security Bulletin Summary

Product:           Siemens SIMATIC S7-1500 CPU
Publisher:         US-CERT
Operating System:  Network Appliance
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2014-5074  

Original Bulletin: 

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Advisory (ICSA-14-226-01) Siemens SIMATIC S7-1500 CPU Denial of Service 
Original release date: August 14, 2014

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Arnaud Ebalard from Agence Nationale de la Scurit des Systmes dInformation 
(ANSSI) has reported a denial-of-service (DoS) vulnerability in Siemens 
SIMATIC S7-1500 CPU. Siemens produced a new firmware version that mitigates 
this vulnerability and then reported it to NCCIC/ICS-CERT.

This vulnerability could be exploited remotely.


The following Siemens SIMATIC S7-1500 CPU versions are affected:

    SIMATIC S7-1500 CPU all versions before V1.6


A successful exploit of this vulnerability will cause the CPU to automatically
restart and remain in the STOP mode. The CPU would then need to be manually 
put into the RUN mode to restore operations.

Impact to individual organizations depends on many factors that are unique to
each organization. ICS-CERT recommends that organizations evaluate the impact
of this vulnerability based on their operational environment, architecture, 
and product implementation.


Siemens is a multinational company headquartered in Munich, Germany.

Products in the Siemens SIMATIC S7-1500 PLC family have been designed for 
discrete and continuous control in industrial environments such as 
manufacturing, food and beverages, and chemical industries worldwide.




Specially crafted TCP packets could cause a DoS of the device if sent in a 
specific order.

CVE-2014-5074 [b] has been assigned to this vulnerability. A CVSS v2 base 
score of 7.1 has been assigned; the CVSS vector string is 
AV:N/AC:M/Au:N/C:N/I:N/A:C. [c]



This vulnerability could be exploited remotely.


No known public exploits specifically target this vulnerability.


An attacker with a moderate skill would be able to exploit this vulnerability.


The firmware update for S7-1500 V1.6 can be obtained at the following location
on the Siemens web site:


Siemens recommends running the affected software components in a protected 
network environment and to configure the environment according to operational
guidelines. [d]

For more information regarding this issue (SSA-310688) or any other security 
issue involving Siemens products, please see the Siemens ProductCERT security
advisory page at:


ICS-CERT encourages asset owners to take additional defensive measures to 
protect against this and other cybersecurity risks.

Minimize network exposure for all control system devices and/or systems, 
and ensure that they are not accessible from the Internet. Locate control 
system networks and remote devices behind firewalls, and isolate them from the
business network. When remote access is required, use secure methods, such as
Virtual Private Networks (VPNs), recognizing that VPNs may have 
vulnerabilities and should be updated to the most current version available. 
Also recognize that VPN is only as secure as the connected devices.

ICS-CERT also provides a section for control systems security recommended 
practices on the ICS-CERT web page at: 
http://ics-cert.us-cert.gov/content/recommended-practices. Several recommended
practices are available for reading and download, including Improving 
Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies. 
ICS-CERT reminds organizations to perform proper impact analysis and risk 
assessment prior to deploying defensive measures.

Additional mitigation guidance and recommended practices are publicly 
available in the ICSCERT Technical Information Paper, 
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation 
Strategies, that is available for download from the ICS-CERT web site 

Organizations observing any suspected malicious activity should follow their 
established internal procedures and report their findings to ICS-CERT for 
tracking and correlation against other incidents.

a. CWE-189: Numeric Errors , 
http://cwe.mitre.org/data/definitions/189.html, web site last accessed August
13, 2014. 

b. NVD, 
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-5074, NIST uses this
advisory to create the CVE web site report. This web site will be active 
sometime after publication of this advisory. 

c. CVSS Calculator, 
http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:M/Au:N/C:N/I:N/A:C, web
site last accessed August 13, 2014. 

d. Operational Guidelines for Industrial Security, 
web site last accessed August 13, 2014.

Contact Information

For any questions related to this report, please contact ICS-CERT at:

Email: ics-cert@hq.dhs.gov Toll Free: 1-877-776-7585 International Callers: 
(208) 526-0900

For industrial control systems security information and incident reporting: 

ICS-CERT continuously strives to improve its products and services. You can 
help by choosing one of the links below to provide feedback about this 

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