1. EXECUTIVE SUMMARY

​CVSS v3 7.5
​ATTENTION: Exploitable remotely/low attack complexity
​Vendor: Mitsubishi Electric
​Equipment: MELSEC-F Series
​Vulnerability: Authentication Bypass by Capture-replay

2. RISK EVALUATION

​Successful exploitation of this vulnerability could allow an attacker to login to the product by sending specially crafted packets.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

​Mitsubishi Electric reports this vulnerability affects the following MELSEC-F Series products if they are used with ethernet communication special adapter FX3U-ENET-ADP or ethernet communication block FX3U-ENET(-L). These products are sold in limited regions:

​FX3U-xMy/z x=16,32,48,64,80,128, y=T,R, z=ES,ESS,DS,DSS *1: All versions
​FX3U-32MR/UA1, FX3U-64MR/UA1 *1: All versions
​FX3U-32MS/ES, FX3U-64MS/ES *1: All versions
​FX3U-xMy/ES-A x=16,32,48,64,80,128, y=T,R *1*2: All versions
​FX3UC-xMT/z x=16,32,64,96, z=D,DSS *1: All versions
​FX3UC-16MR/D-T, FX3UC-16MR/DS-T *1: All versions
​FX3UC-32MT-LT, FX3UC-32MT-LT-2 *1: All versions
​FX3UC-16MT/D-P4, FX3UC-16MR/DSS-P4 *1*2: All versions
​FX3G-xMy/z x=14,24,40,60, y=T,R, z=ES,ESS,DS,DSS *1: All versions
​FX3G-xMy/ES-A x=14,24,40,60, y=T,R *1*2: All versions
​FX3GC-32MT/D, FX3GC-32MT/DSS *1: All versions
​FX3GE-xMy/z x=24,40, y=T,R, z=ES,ESS,DS,DSS *2: All versions
​FX3GA-xMy-CM x=24,40,60, y=T,R *1*2: All versions
​FX3S-xMy/z x=10,14,20,30, y=T,R, z=ES,ESS,DS,DSS *1: All versions
​FX3S-30My/z-2AD y=T,R, z=ES,ESS *1: All versions
​FX3SA-xMy-CM x=10,14,20,30, y=T,R *1*2 : All versions

3.2 VULNERABILITY OVERVIEW

3.2.1 ​AUTHENTICATION BYPASS BY CAPTURE-REPLAY CWE-294

​An authentication bypass vulnerability due to authentication bypass by capture-replay exists in the MELSEC-F series main modules.

​CVE-2023-2846 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:H/A:N).

3.3 BACKGROUND

​CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing

​COUNTRIES/AREAS DEPLOYED: These products are sold in limited regions.

​COMPANY HEADQUARTERS LOCATION: Japan

3.4 RESEARCHER

​Chun Liu, Xin Che, Ruilong Deng, Peng Cheng, and Jiming Chen from 307LAB, Zhejiang University reported this vulnerability to Mitsubishi Electric.

4. MITIGATIONS

​Mitsubishi Electric recommends customers take the following mitigation measures to minimize the risk of an attacker 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.
​Restrict physical access to affected products and the LAN they connect.

​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 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 low attack complexity.