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1. EXECUTIVE SUMMARY

CVSS v3 9.1
ATTENTION: Exploitable remotely/low attack complexity
Vendor: Mitsubishi Electric Corporation
Equipment: MELSEC Series
Vulnerability: Insufficient Verification of Data Authenticity

2. RISK EVALUATION

Successful exploitation of this vulnerability may allow a remote attacker to reset the memory of the products to factory default state and cause a denial-of-service condition.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Mitsubishi Electric reports that the following versions of MELSEC-F series programmable controllers are affected if they are used with ethernet communication special adapter FX3U-ENET-ADP or ethernet communication block FX3U-ENET(-L) with the exception of “FX3GE-xMy/z x=24,40, y=T,R, z=ES,ESS,DS,DSS”. Some of these products are sold in limited regions, see the Mitsubishi Electric advisory for details:

MELSEC-F series FX3U-xMy/z x=16,32,48,64,80,128, y=T,R, z=ES,ESS,DS,DSS: All versions
MELSEC-F series FX3U-32MR/UA1, FX3U-64MR/UA1: All versions
MELSEC-F series FX3U-32MS/ES, FX3U-64MS/ES: All versions
MELSEC-F series FX3U-xMy/ES-A x=16,32,48,64,80,128, y=T,R: All versions
MELSEC-F series FX3UC-xMT/z x=16,32,64,96, z=D,DSS: All versions
MELSEC-F series FX3UC-16MR/D-T, FX3UC-16MR/DS-T: All versions
MELSEC-F series FX3UC-32MT-LT, FX3UC-32MT-LT-2: All versions
MELSEC-F series FX3UC-16MT/D-P4, FX3UC-16MT/DSS-P4: All versions
MELSEC-F series FX3G-xMy/z x=14,24,40,60, y=T,R, z=ES,ESS,DS,DSS: All versions
MELSEC-F series FX3G-xMy/ES-A x=14,24,40,60, y=T,R: All versions
MELSEC-F series FX3GC-32MT/D, FX3GC-32MT/DSS: All versions
MELSEC-F series FX3GE-xMy/z x=24,40, y=T,R, z=ES,ESS,DS,DSS: All versions
MELSEC-F series FX3GA-xMy-CM x=24,40,60, y=T,R: All versions
MELSEC-F series FX3S-xMy/z x=10,14,20,30, y=T,R, z=ES,ESS,DS,DSS: All versions
MELSEC-F series FX3S-30My/z-2AD y=T,R, z=ES,ESS: All versions
MELSEC-F series FX3SA-xMy-CM x=10,14,20,30, y=T,R: All versions
MELSEC iQ-F series FX5U-xMy/z x=32,64,80, y=T,R, z=ES,DS,ESS,DSS: All versions
MELSEC iQ-F series FX5UC-xMy/z x=32,64,96, y=T, z=D,DSS: All versions
MELSEC iQ-F series FX5UC-32MT/DS-TS, FX5UC-32MT/DSS-TS, FX5UC-32MR/DS-TS: All versions
MELSEC iQ-F series FX5UJ-xMy/z x=24,40,60, y=T,R, z=ES,ESS,DS,DSS: All versions
MELSEC iQ-F series FX5UJ-xMy/ES-A x=24,40,60, y=T,R: All versions
MELSEC iQ-F series FX5S-xMy/z x=30,40,60,80, y=T,R, z=ES,ESS: All versions

3.2 Vulnerability Overview

3.2.1 Insufficient Verification of Data Authenticity CWE-345

A denial-of-service vulnerability exists in the MELSEC-F Series main modules and MELSEC iQ-F Series CPU modules. A remote attacker may be able to reset the memory of the products to factory default state and cause a denial-of-service condition on the products by sending specific packets.

CVE-2023-4699 has been assigned to this vulnerability. A CVSS v3.1 base score of 9.1 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H).

3.3 BACKGROUND

CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
COUNTRIES/AREAS DEPLOYED: Worldwide
COMPANY HEADQUARTERS LOCATION: Japan

3.4 RESEARCHER

Mitsubishi Electric reported this vulnerability to CISA.

4. MITIGATIONS

Mitsubishi Electric recommends that customers take the following mitigation measures to minimize the risk of exploiting this vulnerability:

Use a firewall or virtual private network (VPN), etc. to prevent unauthorized access when Internet access is required.
Use within a LAN and block access from untrusted networks and hosts through firewalls.
For MELSEC iQ-F Series, use IP filter function to block access from untrusted hosts. For details on the IP filter function, please refer to the following manual for each product. “12.1 IP Filter Function” in the MELSEC iQ-F FX5 User’s Manual (Ethernet Communication)
Restrict physical access to the affected products and the LAN that is connected by them.

For specific update instructions and additional details see the Mitsubishi Electric advisory.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. 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 this vulnerability has been reported to CISA at this time.

5. UPDATE HISTORY

November 2, 2023: Initial Publication