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AUSCERT External Security Bulletin Redistribution
ESB-2021.3109
Advisory (icsa-21-257-09) Siemens NX
15 September 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens NX
Publisher: ICS-CERT
Operating System: Windows
UNIX variants (UNIX, Linux, OSX)
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Denial of Service -- Existing Account
Access Confidential Data -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2021-37203 CVE-2021-37202
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ICS Advisory (ICSA-21-257-09)
Siemens NX
Original release date: September 14, 2021
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 7.8
o ATTENTION: Low attack complexity
o Vendor: Siemens
o Equipment: NX
o Vulnerabilities: Use After Free, Out-of-bounds Read
2. RISK EVALUATION
Successful exploitation of these vulnerabilities could lead to an access
violation and to arbitrary code execution on the target host system.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of NX are affected:
o NX 1980 Series: All versions prior to v1984
3.2 VULNERABILITY OVERVIEW
3.2.1 USE AFTER FREE CWE-416
The IFC adapter in the affected application contains a use-after-free
vulnerability, which could be triggered while parsing user-supplied IFC files.
An attacker could leverage this vulnerability to execute code in the context of
the current process.
CVE-2021-37202 has been assigned to this vulnerability. A CVSS v3 base score of
7.8 has been calculated; the CVSS vector string is ( AV:L/AC:L/PR:N/UI:R/S:U/
C:H/I:H/A:H ).
3.2.2 OUT-OF-BOUNDS READ CWE-125
The plmxmlAdapterIFC.dll contains an out-of-bounds read while parsing user
supplied IFC files, which could result in a read past the end of an allocated
buffer. This could allow an attacker to cause a denial-of-service condition or
read sensitive information from memory locations.
CVE-2021-37203 has been assigned to this vulnerability. A CVSS v3 base score of
7.1 has been calculated; the CVSS vector string is ( AV:L/AC:L/PR:N/UI:R/S:U/
C:H/I:N/A:H ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
Siemens reported these vulnerabilities to CISA.
4. MITIGATIONS
Siemens has identified the following specific workarounds and mitigations users
can apply to reduce the risk:
o Avoid opening files from unknown sources in NX
o Update to v1984 or later version (login required)
As a general security measure, Siemens strongly recommends users protect
network access to devices with appropriate mechanisms. In order to operate the
devices in a protected IT environment, Siemens recommends users configure the
environment according to Siemens operational guidelines for industrial security
and follow the recommendations in the product manuals.
Additional information on industrial security by Siemens can be found at:
https://www.siemens.com/industrialsecurity
For more information about this issue, please see Siemens Security Advisory
SSA-208530
CISA recommends users take the following measures to protect themselves from
social engineering attacks:
o Do not click web links or open unsolicited attachments in email messages.
o Refer to Recognizing and Avoiding Email Scams for more information on
avoiding email scams.
o Refer to Avoiding Social Engineering and Phishing Attacks for more
information on social engineering attacks.
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.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 us-cert.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 these vulnerabilities. These
vulnerabilities are not exploitable remotely.
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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