Siemens Desigo Fire Safety UL and Cerberus PRO UL Fire Protection Systems

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 10.0
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Siemens
• Equipment: Cerberus PRO UL and Desigo Fire Safety UL
• Vulnerabilities: Classic Buffer Overflow, Out-of-bounds Read, Improper Restriction of Operations within the Bounds of a Memory Buffer

2. RISK EVALUATION

Successful exploitation of the vulnerabilities could allow an unauthenticated attacker, who gained access to the fire protection system network, to execute arbitrary code on the affected products (CVE-2024-22039) or create a denial-of-service condition (CVE-2024-22040, CVE-2024-22041).

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following products of Siemens, are affected:

• Siemens Cerberus PRO UL Compact Panel FC922/924: All versions prior to MP4
• Siemens Cerberus PRO UL Engineering Tool: All versions prior to MP4
• Siemens Cerberus PRO UL X300 Cloud Distribution: All versions prior to V4.3.0001
• Siemens Desigo Fire Safety UL Compact Panel FC2025/2050: All versions prior to MP4
• Siemens Desigo Fire Safety UL Engineering Tool: All versions prior to MP4
• Siemens Desigo Fire Safety UL X300 Cloud Distribution: All versions prior to V4.3.0001

3.2 Vulnerability Overview

3.2.1 BUFFER COPY WITHOUT CHECKING SIZE OF INPUT (‘CLASSIC BUFFER OVERFLOW’) CWE-120

The network communication library in affected systems does not validate the length of certain X.509 certificate attributes which might result in a stack-based buffer overflow. This could allow an unauthenticated remote attacker to execute code on the underlying operating system with root privileges. For Cerberus PRO UL Engineering Tool and Desigo Fire Safety UL Engineering Tool, successful exploitation requires an on-path attacker that intercepts the communication of the engineering tool in the fire system network; code execution might be possible on the underlying operating system with the privileges of the engineering tool user account.

CVE-2024-22039 has been assigned to this vulnerability. A CVSS v3 base score of 10.0 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H).

A CVSS v4 score has been calculated for CVE-2024-22039. A base score of 10.0 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H).

3.2.2 OUT-OF-BOUNDS READ CWE-125

The network communication library in affected systems insufficiently validates HMAC values which might result in a buffer overread. This could allow an unauthenticated remote attacker to crash the network service. For Cerberus PRO UL Engineering Tool and Desigo Fire Safety UL Engineering Tool, successful exploitation requires an on-path attacker that intercepts the communication of the engineering tool in the fire system network; possible impact is limited to the tool, not the underlying operating system.

CVE-2024-22040 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 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:H).

A CVSS v4 score has been calculated for CVE-2024-22040. A base score of 8.7 has been calculated; the CVSS vector string is (CVSS:4.0/V:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H).

3.2.3 IMPROPER RESTRICTION OF OPERATIONS WITHIN THE BOUNDS OF A MEMORY BUFFER CWE-119

The network communication library in affected systems improperly handles memory buffers when parsing X.509 certificates. This could allow an unauthenticated remote attacker to crash the network service. For Cerberus PRO UL Engineering Tool and Desigo Fire Safety UL Engineering Tool, successful exploitation requires an on-path attacker that intercepts the communication of the engineering tool in the fire system network; possible impact is limited to the tool, not the underlying operating system.

CVE-2024-22041 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 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:H).

A CVSS v4 score has been calculated for CVE-2024-22041. A base score of 8.7 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Emergency Services
• COUNTRIES/AREAS DEPLOYED: Worldwide
• 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 risk:

• Cerberus PRO UL Compact Panel FC922/924, Cerberus PRO UL Engineering Tool, Desigo Fire Safety UL Compact Panel FC2025/2050, Desigo Fire Safety UL Engineering Tool: Update to MP4 or later version
• Cerberus PRO UL X300 Cloud Distribution, Desigo Fire Safety UL X300 Cloud Distribution: Update to V4.3.0001 or later version

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-953710 in HTML and CSAF.

CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities, 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.

No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.

5. UPDATE HISTORY

• May 16, 2024: Initial Publication