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AUSCERT External Security Bulletin Redistribution
ESB-2022.4031
Advisory (icsa-22-104-12) Siemens SIMATIC S7-400 (Update A)
12 August 2022
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens SIMATIC S7-400
Publisher: ICS-CERT
Operating System: Network Appliance
Resolution: Patch/Upgrade
CVE Names: CVE-2021-40368
Original Bulletin:
https://us-cert.cisa.gov/ics/advisories/icsa-22-104-12
Comment: CVSS (Max): 7.5 CVE-2021-40368 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVSS Source: ICS-CERT
Calculator: https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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ICS Advisory (ICSA-22-104-12)
Siemens SIMATIC S7-400 (Update A)
Original release date: August 11, 2022
Legal Notice
All information products included in https://us-cert.cisa.gov/ics 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 https://us-cert.cisa.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 7.5
o ATTENTION: Exploitable remotely/low attack complexity
o Vendor: Siemens
o Equipment: SIMATIC S7-400
o Vulnerability: Improper Restriction of Operations within the Bounds of a
Memory Buffer
2. UPDATE
This updated advisory is a follow-up to the advisory update titled
ICSA-21-104-12 Siemens SIMATIC S7-400 that was published April 14, 2022, to the
ICS webpage on www.cisa.gov/ics.
3. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to create
a denial-of-service condition.
4. TECHNICAL DETAILS
4.1 AFFECTED PRODUCTS
The following Siemens S7-400 products are affected:
o SIMATIC S7-400 HV6 CPU family (incl. SIPLUS variants): All versions prior
to v6.0.10
o SIMATIC S7-400 PN/DP V7 CPU family (incl. SIPLUS variants): All versions
- --------- Begin Update A Part 1 of 2 ---------
o SIMATIC S7-410 V8 CPU family (incl. SIPLUS variants): All versions prior to
v8.2.3
- --------- End Update A Part 1 of 2 ---------
o SIMATIC S7-410 V10 CPU family (incl. SIPLUS variants): All versions prior
to v10.1
4.2 VULNERABILITY OVERVIEW
4.2.1 IMPROPER RESTRICTION OF OPERATIONS WITHIN THE BOUNDS OF A MEMORY BUFFER
CWE-119
Affected devices improperly handle specially crafted packets sent to Port 102/
TCP. This could allow an attacker to create a Denial-of-Service condition. A
restart is needed to restore normal operations.
CVE-2021-40368 has been assigned to this vulnerability. A CVSS v3 base score of
7.5 has been assigned; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:U/C:N/
I:N/A:H ).
4.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Multiple Sectors
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
4.4 RESEARCHER
Siemens reported this vulnerability to CISA.
5. MITIGATIONS
Siemens recommends updating their software to the most current version where
available:
o SIMATIC S7-400 HV6 CPU family (incl. SIPLUS variants): Update to v6.0.10 or
later
o SIMATIC S7-400 PN/DP V7 CPU family (incl. SIPLUS variants): No current fix
is available
- --------- Begin Update A Part 2 of 2 ---------
o SIMATIC S7-410 V8 CPU family (incl. SIPLUS variants): Update to v8.2.3 or
later
- --------- End Update A Part 2 of 2 ---------
o SIMATIC S7-410 V10 CPU family (incl. SIPLUS variants): Update to v10.1 or
later
o To obtain SIMATIC S7-410 v10.1 contact Siemens support
Siemens has identified the following specific workarounds and mitigations users
can apply to reduce the risk:
o Limit access to Port 102/TCP to trusted users and systems only
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 the Siemens operational guidelines for industrial security and
following the recommendations in the product manuals.
For additional information, please refer to Siemens Security Advisory
SSA-557541
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 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 VPNs may have vulnerabilities and should be
updated to the most current version available. Also recognize VPN is only
as secure as its 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 cisa.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 cisa.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.
No known public exploits specifically target this vulnerability.
For any questions related to this report, please contact the CISA at:
Email: CISAservicedesk@cisa.dhs.gov
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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