Schneider Electric Modicon M340, MC80, and Momentum Unity M1E Improper Restriction of Operations Within the Bounds of a Memory Buffer (CVE-2024-8937)

medium Tenable OT Security Plugin ID 502685

Synopsis

The remote OT asset is affected by a vulnerability.

Description

Arbitrary code execution can potentially be achieved after a successful Man-In-The Middle attack followed by sending a crafted Modbus function call to tamper with memory area involved in the authentication process.

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Solution

The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at CISA.gov.

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-momentumIf 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.

Plugin Details

Severity: Medium

ID: 502685

Version: 1.4

Type: remote

Family: Tenable.ot

Published: 11/28/2024

Updated: 4/18/2025

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 4.2

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:schneider-electric:modicon_mc80, cpe:/o:schneider-electric:modicon_momentum_171cbu78090_firmware, cpe:/o:schneider-electric:modicon_momentum_171cbu98090_firmware, cpe:/o:schneider-electric:modicon_m340, cpe:/o:schneider-electric:modicon_momentum_171cbu98091_firmware

Required KB Items: Tenable.ot/Schneider

Exploit Ease: No known exploits are available

Patch Publication Date: 11/12/2024

Vulnerability Publication Date: 11/12/2024

Reference Information

CVE: CVE-2024-8937

CWE: 119

ICSA: 24-326-04

Detections

Analytics