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AUSCERT External Security Bulletin Redistribution
ESB-2019.4315.2
Advisory (icsa-19-318-02) Siemens S7-1200 CPU
11 December 2019
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens S7-1200 CPU
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Access Confidential Data -- Console/Physical
Resolution: Mitigation
CVE Names: CVE-2019-13945
Original Bulletin:
https://www.us-cert.gov/ics/advisories/icsa-19-318-02
Revision History: December 11 2019: Added Update A
November 15 2019: Initial Release
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ICS Advisory (ICSA-19-318-02)
Siemens S7-1200 and S7-200 SMART CPUs (Update A)
Original release date: December 10, 2019
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/ .
1. EXECUTIVE SUMMARY
o CVSS v36.8
o ATTENTION : Low skill level to exploit
o Vendor : Siemens
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o Equipment: S7-1200 CPU family (including SIPLUS variants); S7-200 SMART CPU
family
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o Vulnerability : Exposed Dangerous Method or Function
2. UPDATE INFORMATION
This updated advisory is a follow-up to the original advisory titled
ICSA-19-318-02 Siemens S7-1200 that was published November 14, 2019, on the ICS
webpage on us-cert.gov.
2. RISK EVALUATION
Successful exploitation of this vulnerability could expose additional
diagnostic functionality to an attacker with physical access to the UART
interface during boot process.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following Siemens products are affected:
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o S7-1200 CPU family (including SIPLUS variants): all versions
o S7-200 SMART CPU: all versions
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3.2 VULNERABILITY OVERVIEW
3.2.1 EXPOSED DANGEROUS METHOD OR FUNCTION CWE-749
An attacker with physical access to the UART interface could access additional
diagnostic functionality. Successful exploitation could compromise
confidentiality, integrity, and availability of the affected system.
CVE-2019-13945 has been assigned to this vulnerability. A CVSS v3 base score of
6.8 has been calculated; the CVSS vector string is
( AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS : Chemical, Critical Manufacturing, Energy,
Food and Agriculture, Water and Wastewater Systems
o COUNTRIES/AREAS DEPLOYED : Worldwide
o COMPANY HEADQUARTERS LOCATION : Germany
3.4 RESEARCHER
Ali Abbasi from Ruhr University of Bochum reported this vulnerability to
Siemens.
4. MITIGATIONS
Siemens has identified the following specific workarounds and mitigations that
users of the S7-122 CPU can apply to reduce the risk:
o Ensure physical access protection.
o Apply Defense-in-Depth .
As a general security measure, Siemens strongly recommends protecting network
access to devices with appropriate mechanisms. Siemens recommends users
configure their environment according to the Siemens Operational Guidelines for
Industrial Security and follow the recommendations in the product manuals to
operate the devices in a protected environment.
Additional information on industrial security by Siemens can be found at:
https://www.siemens.com/industrialsecurity.
For further inquiries on security vulnerabilities in Siemens products, please
contact the Siemens ProductCERT: http://www.siemens.com/cert/advisories.
For more information on the vulnerability and more detailed mitigation
instructions, please see Siemens Security Advisory SSA-686531 at the following
location: http://www.siemens.com/cert/advisories.
CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:
o Minimize network exposure for all control system devices and/or systems,
and ensure that they are not accessible from the Internet .
o Locate control system networks and remote devices behind firewalls, and
isolate them from the business network.
o 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.
CISA reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices
on the ICS webpage on us-cert.gov . 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
on the ICS webpage on us-cert.gov in the Technical Information Paper,
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies .
Organizations observing any suspected malicious activity should follow their
established internal procedures and report their findings to CISA for tracking
and correlation against other incidents.
This vulnerability is not exploitable remotely; no known public exploits
specifically target this vulnerability.
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