Siemens APOGEE, TALON and Desigo PXC/PXM Products

1. EXECUTIVE SUMMARY

• CVSS v3 9.8
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Siemens
• Equipment: FTP Server of Nucleus RTOS based APOGEE, TALON and Desigo PXC/PXM Products
• Vulnerabilities: Uncontrolled Resource Consumption

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow a remote attacker to generate a denial-of-service condition on devices incorporating a vulnerable version of the file transfer protocol (FTP) server.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Siemens reports this vulnerability affects the following products which use FTP Server of Nucleus RTOS: 

• APOGEE MBC (PPC) (BACnet): All versions
• APOGEE MBC (PPC) (P2 Ethernet): All versions
• APOGEE MEC (PPC) (BACnet): All versions
• APOGEE MEC (PPC) (P2 Ethernet): All versions
• APOGEE PXC Compact (BACnet): All versions
• APOGEE PXC Compact (P2 Ethernet): All versions
• APOGEE PXC Modular (BACnet): All versions
• APOGEE PXC Modular (P2 Ethernet): All versions
• Desigo PXC00-E.D: All versions since and including V2.3
• Desigo PXC00-U: All versions since and including V2.3
• Desigo PXC001-E.D: All versions since and including V2.3
• Desigo PXC12-E.D: All versions since and including V2.3
• Desigo PXC22-E.D: All versions since and including V2.3
• Desigo PXC22.1-E.D: All versions since and including V2.3
• Desigo PXC36.1-E.D: All versions since and including V2.3
• Desigo PXC50-E.D: All versions since and including V2.3
• Desigo PXC64-U: All versions since and including V2.3
• Desigo PXC100-E.D: All versions since and including V2.3
• Desigo PXC128-U: All versions since and including V2.3
• Desigo PXC200-E.D: All versions since and including V2.3
• Desigo PXM20-E: All versions since and including V2.3
• TALON TC Compact (BACnet): All versions
• TALON TC Modular (BACnet): All versions

3.2 VULNERABILITY OVERVIEW

3.2.1    UNCONTROLLED RESOURCE CONSUMPTION CWE-400

The FTP server does not properly release memory resources reserved for incomplete connection attempts by FTP clients. This could allow a remote attacker to generate a denial-of-service condition on devices incorporating a vulnerable version of the FTP server.

CVE-2022-38371 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities, Government Facilities 
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Siemens ProductCERT reported this vulnerability to CISA.

4. MITIGATIONS

Siemens is preparing updates and recommends specific countermeasures for products where updates are in process or are not yet available:

• Disable the FTP service 

Note: The FTP service is disabled by default on APOGEE, Desigo, and TALON products.

As a general security measure, Siemens strongly recommends protecting network access to affected products with appropriate mechanisms and advises users follow recommended security practices to run devices in a protected IT environment.

Siemens has provided additional information on industrial security on the Siemens Industrial Security web page.

For more information, see the associated Siemens Security Advisory SSA-935500 in HTML or CSAF formats.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability these vulnerabilities. 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 this vulnerability. This vulnerability is exploitable remotely. This vulnerability has a low attack complexity.