Schneider Electric Modicon M340, MC80, and Momentum Unity M1E (Update A)

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1. EXECUTIVE SUMMARY

• CVSS v4 9.2
• ATTENTION: Exploitable remotely
• Vendor: Schneider Electric
• Equipment: Modicon M340, MC80, and Momentum Unity M1E
• Vulnerabilities: Improper Input Validation, Improper Restriction of Operations within the Bounds of a Memory Buffer

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to tamper with memory on the affected devices.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Schneider Electric Modicon M340, MC80, and Momentum Unity M1E are affected:

• Modicon M340 CPU (part numbers BMXP34*): Versions prior to SV3.65
• Modicon MC80 (part numbers BMKC80): All versions (CVE-2024-8937, CVE-2024-8938)
• Modicon Momentum Unity M1E Processor (171CBU*): Versions prior to SV2.80 (CVE-2024-8937, CVE-2024-8938)

3.2 VULNERABILITY OVERVIEW

3.2.1 IMPROPER INPUT VALIDATION CWE-20

CWE-20: Improper Input Validation vulnerability exists that could lead to tampering with a parameter of the controller memory after a successful Man-In-The-Middle attack followed by Read Physical Memory operation leading to loss of confidentiality of controller memory.

CVE-2024-8936 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.5 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N).

A CVSS v4 score has also been calculated for CVE-2024-8936. A base score of 8.3 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N).

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

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability exists that could cause potential arbitrary code execution after a successful Man-In-The-Middle attack followed by sending crafted Modbus command to tamper with a function call used for authentication process.

CVE-2024-8937 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.1 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H).

A CVSS v4 score has also been calculated for CVE-2024-8937. A base score of 9.2 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N).

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

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability exists that could cause potential arbitrary code execution after a successful Man-In-The-Middle attack followed by sending crafted Modbus command in order to tamper with a function call used to evaluate memory size.

CVE-2024-8938 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.1 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H).

A CVSS v4 score has also been calculated for CVE-2024-8938. A base score of 9.2 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities, Critical Manufacturing, Energy
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: France

3.4 RESEARCHER

Amir Zaltzman of Tel Aviv University reported these vulnerabilities to Schneider Electric.

4. MITIGATIONS

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

Schneider Electric Modicon M340 CPU (part numbers BMXP34*) Versions prior to SV3.65:

• Version SV3.65 of Modicon M340 firmware includes a fix for these vulnerabilities and is available for download here: https://www.se.com/ww/en/product-range/1468- modicon-m340

If customers choose not to apply the remediation provided above, they should immediately apply the following mitigations to reduce the risk of exploit:

• Set up network segmentation and implement a firewall to block all unauthorized access to port 502/TCP
• Configure the Access Control List following the recommendations of the user manuals: "Modicon M340 for Ethernet Communications Modules and Processors User Manual" chapter "Messaging Configuration Parameters": https://www.se.com/ww/en/download/document/31007131K01000/
• Consider use of external firewall devices such as EAGLE40-07 from Belden to establish VPN connections. For more details refer to "Modicon Controller Systems Cybersecurity, User Guide": https://www.se.com/ww/en/download/document/EIO0000001999/
• Ensure the M340 CPU is running with the memory protection activated by configuring the input bit to a physical input, for more details refer to the following guideline "Modicon Controller Systems Cybersecurity, User Guide" chapter "Controler Memory Protection": https://www.se.com/ww/en/download/document/EIO0000001999/
• Setup network segmentation and implement a firewall to block all unauthorized access to port 502/TCP
• Consider use of external firewall devices such as EAGLE40-07 from Belden to establish VPN connections. For more details refer to "Modicon Controller Systems Cybersecurity, User Guide": https://www.se.com/ww/en/download/document/EIO0000001999/
• Ensure the M340 CPU is running with the memory protection activated by configuring the input bit to a physical input, for more details refer to the following guideline "Modicon Controller Systems Cybersecurity, User Guide" chapter "Controler Memory Protection": https://www.se.com/ww/en/download/document/EIO0000001999/

Schneider Electric Modicon MC80 (part numbers BMKC80) All versions:

Schneider Electric is establishing a remediation plan for all future versions of Modicon MC80 that will include fixes for CVE-2024-8937 and CVE-2024- 8938. Schneider Electric will update this document when the remediations are available. Until then, customers should immediately apply the following mitigations to reduce the risk of exploit:

• Setup network segmentation and implement a firewall to block all unauthorized access to port 502/TCP
• Configure the Access Control List following the recommendations of the user manuals: "MC80 Programmable Logic Controller (PLC), User Manual" in the section "Access Control List (ACL)": https://www.se.com/ww/en/download/document/EIO0000002071/
• Consider use of external firewall devices such as EAGLE40-07 from Belden to establish VPN connections. For more details refer to "Modicon Controller Systems Cybersecurity, User Guide": https://www.se.com/ww/en/download/document/EIO0000001999/

Schneider Electric Modicon Momentum Unity M1E Processor (171CBU*) Versions prior to SV2.80:

• Version SV2.80 of Modicon Momentum firmware includes a fix for these vulnerabilities and is available for download here: https://www.se.com/ww/en/product-range/535-modicon-momentum

  If customers choose not to apply the remediation provided above, they should immediately apply the following mitigations to reduce the risk of exploit:

• Setup network segmentation and implement a firewall to block all unauthorized access to port 502/TCP
• Configure the Access Control List following the recommendations of the user manuals: "Momentum for EcoStruxure Control Expert -171CBU78090, 171CBU98090, 171CBU98091 Processors, User Guide" in the section "Controlling Access": https://www.se.com/ww/en/download/document/HRB44124/
• Consider use of external firewall devices such as EAGLE40-07 from Belden to establish VPN connections. For more details refer to "Modicon Controller Systems Cybersecurity, User Guide": https://www.se.com/ww/en/download/document/EIO0000001999/

For more information see the associated Schneider Electric CPCERT security advisory SEVD-2024-317-03 Modicon Controllers M340 / Momentum / MC80 - SEVD-2024-317-03 PDF Version, Modicon Controllers M340 / Momentum / MC80 - SEVD-2024-317-03 CSAF Version.

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), 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.

No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time. These vulnerabilities have a high attack complexity.

5. UPDATE HISTORY

• November 21, 2024: Initial Republication Schneider Electric CPCERT SEVD-2024-317-03
• April 17, 2025: Update A - A remediation is now available for Modicon Momentum Unity M1E Processor.

• Schneider Electric