As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemens’ ProductCERT Security Advisories (CERT Services | Services | Siemens Global).
1. EXECUTIVE SUMMARY
CVSS v4 7.0
ATTENTION: Low attack complexity
Vendor: Siemens
Equipment: TIA Portal and SIMATIC STEP 7
Vulnerability: Deserialization of Untrusted Data
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to cause a type confusion and execute arbitrary
code within the affected application.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following products of Siemens, are affected:
Totally Integrated Automation Portal (TIA Portal): All versions
Totally Integrated Automation Portal (TIA Portal) V18: All versions
SIMATIC STEP 7 Safety V18: All versions
3.2 Vulnerability Overview
3.2.1 DESERIALIZATION OF UNTRUSTED DATA CWE-502
Affected applications do not properly restrict the .NET BinaryFormatter when deserializing user-controllable
input. This could allow an attacker to cause a type confusion and execute arbitrary code within the affected application. This is the same issue that exists for .NET BinaryFormatter https://docs.microsoft.com/enus/visualstudio/code-quality/ca2300.
CVE-2023-32737 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.3 has been calculated; the CVSS vector string is (AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H).
A CVSS v4 score has also been calculated for CVE-2023-32737. A base score of 7.0 has been calculated; the CVSS vector string is (CVSS4.0/AV:L/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N).
3.3 BACKGROUND
CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
COUNTRIES/AREAS DEPLOYED: Worldwide
COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
Siemens reported this vulnerability to CISA.
4. MITIGATIONS
Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:
Totally Integrated Automation Portal (TIA Portal): Update to V18 Update 2 or later version
Totally Integrated Automation Portal (TIA Portal) V18: Update to V18 Update 2 or later version
SIMATIC STEP 7 Safety V18: Update to V18 Update 2 or later version
Siemens has identified the following specific workarounds and mitigations that customers can apply to
reduce the risk:
Avoid uploading PLC software from untrusted devices or MMC cards
As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. 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.
Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage
For more information see the associated Siemens security advisory SSA-313039 in HTML and CSAF.
CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability, such as:
Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
Locate control system networks and remote devices behind firewalls and isolating them from business networks.
When remote access is required, use more 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 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 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.
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.
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.
CISA also recommends users take the following measures to protect themselves from social engineering attacks:
Do not click web links or open attachments in unsolicited email messages.
Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams.
Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks.
No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time. This vulnerability is not exploitable remotely.
5. UPDATE HISTORY
July 11, 2024: Initial Publication