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AUSCERT External Security Bulletin Redistribution
ESB-2023.3941
ICS Advisory | ICSA-22-194-03 Siemens SIMATIC CN 4100
14 July 2023
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AusCERT Security Bulletin Summary
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Product: Siemens SIMATIC CN 4100
Publisher: ICS-CERT
Operating System: Network Appliance
Resolution: Patch/Upgrade
CVE Names: CVE-2023-29131 CVE-2023-29130
Original Bulletin:
https://www.cisa.gov/news-events/ics-advisories/icsa-22-194-03
Comment: CVSS (Max): 9.9 CVE-2023-29130 (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H)
CVSS Source: ICS-CERT
Calculator: https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
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ICS Advisory (ICSA-22-194-03)
Siemens SIMATIC CN 4100
Release Date
July 13, 2023
1. EXECUTIVE SUMMARY
o CVSS v3 9.9
o ATTENTION: Exploitable remotely/low attack complexity
o Vendor: Siemens
o Equipment: SIMATIC CN 4100
o Vulnerabilities: Improper Access Control, Incorrect Default Permissions
2. RISK EVALUATION
Successful exploitation of these vulnerabilities could allow an attacker to
gain privilege escalation and bypass network isolation.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of Siemens SIMATIC CN 4100, a communication node, are
affected:
o SIMATIC CN 4100: all versions prior to V2.5
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER ACCESS CONTROL CWE-284
Affected device consists of improper access controls in the configuration files
that could lead to privilege escalation. An attacker could gain admin access
with this vulnerability, leading to complete device control.
CVE-2023-29130 has been assigned to this vulnerability. A CVSS v3 base score of
9.9 has been assigned; the CVSS vector string is ( AV:N/AC:L/PR:L/UI:N/S:C/C:H/
I:H/A:H ).
3.2.2 INCORRECT DEFAULT PERMISSIONS CWE-276
Affected device consists of an incorrect default value in the SSH
configuration. This could allow an attacker to bypass network isolation.
CVE-2023-29131 has been assigned to this vulnerability. A CVSS v3 base score of
7.4 has been assigned; the CVSS vector string is ( AV:N/AC:L/PR:L/UI:N/S:C/C:L/
I:L/A:L ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Multiple
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
Michael Klassen and Martin Floeck of BASF Security Team reported these
vulnerabilities to Siemens.
4. MITIGATIONS
Siemens identified the following specific workarounds and mitigations users can
apply to reduce risk:
o SIMATIC CN 4100: Update to V2.5 or later version.
As a general security measure, Siemens 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 recommendations in the product manuals.
For more information, see the associated Siemens Security Advisory SSA-313488
in HTML and CSAF .
CISA recommends users take defensive measures to minimize the risk of
exploitation of these vulnerabilities. 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 business networks.
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 at cisa.gov/ics . Several CISA products detailing cyber
defense best 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 at cisa.gov/ics in the technical information paper,
ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation
Strategies .
Organizations observing suspected malicious activity should follow established
internal procedures and report findings to CISA for tracking and correlation
against other incidents.
No known public exploits specifically target these vulnerabilities.
This product is provided subject to this Notification and this Privacy & Use
policy.
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