Siemens COMOS

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, see Siemens’ ProductCERT Security Advisories (CERT Services | Services | Siemens Global).

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1. EXECUTIVE SUMMARY

• CVSS v4 5.9
• ATTENTION: Low Attack Complexity
• Vendor: Siemens
• Equipment: COMOS
• Vulnerabilities: Improper Restriction of XML External Entity Reference

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to extract arbitrary application files.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Siemens reports that the following products are affected:

• COMOS V10.4.0: All versions
• COMOS V10.4.1: All versions
• COMOS V10.4.2: All versions
• COMOS V10.4.3: Versions prior to V10.4.3.0.47
• COMOS V10.4.4: Versions prior to V10.4.4.2
• COMOS V10.4.4.1: Versions prior to V10.4.4.1.21
• COMOS V10.3: Versions prior to V10.3.3.5.8

3.2 Vulnerability Overview

3.2.1 IMPROPER RESTRICTION OF XML EXTERNAL ENTITY REFERENCE CWE-611

The Generic Data Mapper, the Engineering Adapter, and the Engineering Interface improperly handle XML External Entity (XXE) entries when parsing configuration and mapping files. This could allow an attacker to extract any file with a known location on the user’s system or accessible network folders by persuading a user to use a maliciously crafted configuration or mapping file in one of the affected components.

CVE-2024-49704 has been assigned to this vulnerability. A CVSS v3 base score of 5.5 has been assigned; the CVSS vector string is (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N).

A CVSS v4 score has also been calculated for CVE-2024-49704. A base score of 5.7 has been calculated; the CVSS vector string is (CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N).

3.2.2 IMPROPER RESTRICTION OF XML EXTERNAL ENTITY REFERENCE CWE-611

The PDMS/E3D Engineering Interface improperly handles XML External Entity (XXE) entries when communicating with an external application. This could allow an attacker to extract any file with a known location on the user’s system or accessible network folders by injecting malicious data into the communication channel between the two systems.

CVE-2024-54005 has been assigned to this vulnerability. A CVSS v3 base score of 5.1 has been assigned; the CVSS vector string is (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N).

A CVSS v4 score has also been calculated for CVE-2024-54005. A base score of 5.9 has been calculated; the CVSS vector string is (CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/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 these vulnerabilities to CISA.

4. MITIGATIONS

Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:

• COMOS V10.3: Update to V10.3.3.5.8 or later version. The patch is available upon request from customer support
• COMOS V10.4.0, COMOS V10.4.1, COMOS V10.4.2: Currently no fix is planned
• COMOS V10.4.3: Update to V10.4.3.0.47 or later version. The patch is available upon request from customer support
• COMOS V10.4.4: Update to V10.4.4.2 or later version
• COMOS V10.4.4.1: Update to V10.4.4.1.21 or later version
• For CVE-2024-49704: Do not use untrusted configuration and mapping files. Ensure that only authorized users can modify the files by implementing appropriate security settings. Simply setting the “read-only” property is not a sufficient security measure.
• For CVE-2024-54005: Make sure that only administrators have write-access to the configuration files, especially the network configuration. Simply setting the “read-only” property is not a sufficient security measure.

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-701627 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.

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 these vulnerabilities has been reported to CISA at this time. These vulnerabilities are not exploitable remotely.

5. UPDATE HISTORY

• December 12, 2024: Initial Publication