Siemens SIMATIC and SIMIT

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).

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1. EXECUTIVE SUMMARY

• CVSS v3 5.3
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Siemens
• Equipment: SIMATIC, SIMIT
• Vulnerability: Improperly Controlled Sequential Memory Allocation

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker to cause a high load situation, memory exhaustion, and may block the server.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following products of Siemens, are affected:

• SIMATIC Energy Manager Basic: Versions prior to V7.5
• SIMATIC Energy Manager PRO: Versions prior to V7.5
• SIMATIC IPC DiagBase: All versions
• SIMATIC IPC DiagMonitor: All versions
• SIMIT V10: All versions
• SIMIT V11: Versions prior to V11.1

3.2 Vulnerability Overview

3.2.1 IMPROPERLY CONTROLLED SEQUENTIAL MEMORY ALLOCATION CWE-1325

Unified Automation .NET based OPC UA Server SDK before 3.2.2 used in Siemens products are affected by a similar vulnerability as documented in CVE-2023-27321 for the OPC Foundation UA .NET Standard implementation. A successful attack may lead to high load situation and memory exhaustion, and may block the server.

CVE-2023-52891 has been assigned to this vulnerability. A CVSS v3 base score of 5.3 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

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:

• SIMIT V11: Update to V11.1 or later version
• SIMATIC Energy Manager Basic, SIMATIC Energy Manager PRO: Update to V7.5 or later version
• Disable the OPC UA server in the affected product, if possible and OPC UA is not used
• Restrict access to the OPC UA interface to trusted clients
• SIMATIC IPC DiagBase, SIMATIC IPC DiagMonitor: Currently no fix is available
• SIMIT V10: Currently no fix is planned

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-088132 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). Recognize VPNs may have vulnerabilities, should be updated to the most recent version available, and are 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. 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 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.

5. UPDATE HISTORY

• July 11, 2024: Initial Publication

• Siemens