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AUSCERT External Security Bulletin Redistribution
ESB-2016.0712
Siemens SIMATIC S7-1200 CPU Protection Mechanism Failure
17 March 2016
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens SIMATIC S7-1200
Publisher: US-CERT
Operating System: Network Appliance
Impact/Access: Reduced Security -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2016-2846
Original Bulletin:
https://ics-cert.us-cert.gov/advisories/ICSA-16-075-01
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Advisory (ICSA-16-075-01)
Siemens SIMATIC S7-1200 CPU Protection Mechanism Failure
Original release date: March 15, 2016
Legal Notice
All information products included in http://ics-cert.us-cert.gov are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
contained within. DHS does not endorse any commercial product or service,
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For
more information about TLP, see http://www.us-cert.gov/tlp/.
OVERVIEW
Siemens has identified a protection mechanism failure vulnerability in old
firmware versions of SIMATIC S7-1200. Maik Brggemann and Ralf Spenneberg from
Open Source Training reported this issue directly to Siemens. Siemens provides
SIMATIC S7-1200 CPU product, release V4.0 or newer, to mitigate this
vulnerability and recommends keeping the firmware up to date.
This vulnerability could be exploited remotely.
AFFECTED PRODUCTS
Siemens reports that the vulnerability affects the following SIMATIC products:
SIMATIC S7-1200 CPU family: All versions prior to V4.0
IMPACT
An attacker who exploits this vulnerability could circumvent user program
block protection.
Impact to individual organizations depends on many factors that are unique to
each organization. NCCIC/ICS-CERT recommends that organizations evaluate the
impact of this vulnerability based on their operational environment,
architecture, and product implementation.
BACKGROUND
Siemens is a multinational company headquartered in Munich, Germany.
The affected products, the Siemens SIMATIC S7-1200 CPU family, are designed
for discrete and continuous control in industrial environments. According to
Siemens, the Siemens SIMATIC S7-1200 CPU family is deployed across several
sectors including Chemical, Critical Manufacturing, and Food and Agriculture.
Siemens estimates that these products are used worldwide.
VULNERABILITY CHARACTERIZATION
VULNERABILITY OVERVIEW
PROTECTION MECHANISM FAILURE [a]
SIMATIC S7-1200 CPU firmware prior to Version 4.0 could possibly allow an
attacker to circumvent user program block protection under certain
circumstances.
CVE-2016-2846 [b] has been assigned to this vulnerability. A CVSS v3 base
score of 6.5 has been assigned; the CVSS vector string is
(AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N). [c]
VULNERABILITY DETAILS
EXPLOITABILITY
This vulnerability could be exploited remotely.
EXISTENCE OF EXPLOIT
No known public exploits specifically target this vulnerability.
DIFFICULTY
An attacker with a low skill would be able to exploit this vulnerability.
MITIGATION
Siemens recommends firmware release Version 4.0 or later for SIMATIC S7-1200
CPUs. Siemens recommends to keep firmware up to date and to set the PLC
functionality Access protection to read/write protection. The latest firmware
releases can be found here:
http://support.automation.siemens.com/WW/view/en/106200276
For more information on these vulnerabilities and detailed instructions,
please see Siemens Security Advisory SSA-833048 at the following location:
http://www.siemens.com/cert/advisories
As a general security measure Siemens strongly recommends to protect network
access to the web interface of S7-1200 CPUs with appropriate mechanisms.
Siemens advises to configure the environment according to Siemens operational
guidelines in order to run the devices in a protected IT environment.
ICS-CERT recommends that users take defensive measures to minimize the risk of
exploitation of these vulnerabilities. Specifically, users should:
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 reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
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.
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
(http://ics-cert.us-cert.gov/).
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-693: Protection Mechanism Failure,
http://cwe.mitre.org/data/definitions/693.html, web site last accessed March
15, 2016.
b. NVD, https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-2846
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,
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S...,
web site last accessed March 15, 2016.
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:
http://ics-cert.us-cert.gov
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
product.
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