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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-20-252-02) Siemens SIMATIC S7-300 and S7-400 CPUs
14 October 2020
AusCERT Security Bulletin Summary
Product: Siemens SIMATIC S7-300
Operating System: Network Appliance
Impact/Access: Access Confidential Data -- Remote/Unauthenticated
CVE Names: CVE-2020-15791
Revision History: October 14 2020: Release of minor update A
September 9 2020: Initial Release
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ICS Advisory (ICSA-20-252-02)
Siemens SIMATIC S7-300 and S7-400 CPUs (Update A)
Original release date: October 13, 2020
All information products included in https://us-cert.gov/ics are provided"as
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does not provide any warranties of any kind regarding any information contained
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1. EXECUTIVE SUMMARY
o CVSS v3 5.3
o ATTENTION: Low skill level to exploit
o Vendor: Siemens
o Equipment: SIMATIC S7-300 and S7-400 CPUs
o Vulnerability: Insufficiently Protected Credentials
2. UPDATE INFORMATION
This updated advisory is a follow-up to the original advisory titled
ICSA-20-252-02 Siemens SIMATIC S7-300 and S7-400 CPUs that was published
September 8, 2020, to the ICS webpage on us-cert.gov.
3. RISK EVALUATION
Successful exploitation of this vulnerability could result in credential
4. TECHNICAL DETAILS
4.1 AFFECTED PRODUCTS
Siemens reports the vulnerability affects the following versions of SIMATIC
S7-300 and S7-400 CPU families:
o SIMATIC S7-300 CPU family (incl. related ET200 CPUs and SIPLUS variants):
o SIMATIC S7-400 CPU family (incl. SIPLUS variants): All versions
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o SIMATIC WinAC RTX (F) 2010: All versions
o SINUMERIK 840D sl: All versions
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4.2 VULNERABILITY OVERVIEW
4.2.1 INSUFFICIENTLY PROTECTED CREDENTIALS CWE-522
The authentication protocol between a client and a PLC via Port 102/TCP
(ISO-TSAP) insufficiently protects the transmitted password. This could allow
an attacker that is able to intercept the network traffic to obtain valid PLC
CVE-2020-15791 has been assigned to this vulnerability. A CVSS v3 base score of
5.3 has been calculated; the CVSS vector string is ( AV:A/AC:H/PR:N/UI:N/S:U/
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
Hyunguk Yoo from University of New Orleans and Irfan Ahmed and Adeen Ayub from
Virginia Commonwealth University reported this vulnerability to Siemens.
Siemens has identified the following specific workarounds and mitigations users
can apply to reduce the risk:
o Apply defense-in-depth concepts .
o Apply cell protection concepts .
o For SIMATIC S7-CPU 410 CPUs: Activate field interface security in PCS 7
v9.0, and use a CP443-1 Adv. to communicate with ES/OS
As a general security measure, Siemens strongly recommends protecting network
access to devices with appropriate mechanisms. In order to operate the devices
in a protected IT environment, Siemens recommends configuring the environment
according to Siemens' operational guidelines for Industrial Security , and
following the recommendations in the product manuals.
Follow this link for additional information on Industrial Security by Siemens .
For more information on this vulnerability and the associated mitigations,
please see Siemens security advisory SSA-381684
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
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.
No known public exploits specifically target this vulnerability. This
vulnerability is not exploitable from adjacent networks.
For any questions related to this report, please contact the CISA at:
Toll Free: 1-888-282-0870
CISA 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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