Mitsubishi Electric MELSEC WS Series Ethernet Interface Module

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1. EXECUTIVE SUMMARY

• CVSS v3 5.9
• ATTENTION: Exploitable remotely
• Vendor: Mitsubishi Electric
• Equipment: MELSEC WS Series
• Vulnerability: Authentication Bypass by Capture-replay

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an unauthorized attacker to login to the modules and disclose or tamper with the programs and parameters in the modules.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Mitsubishi Electric MELSEC WS Series Ethernet Interface Modules, are affected:

• WS0-GETH00200: All serial numbers

3.2 Vulnerability Overview

3.2.1 AUTHENTICATION BYPASS BY CAPTURE-REPLAY CWE-294

An authentication bypass vulnerability exists in the MELSEC WS Series Ethernet Interface Modules. A remote unauthenticated attacker can bypass authentication by capture-replay attack and login to the modules. As a result, the remote attacker who has logged in may be able to disclose or tamper with the programs and parameters in the modules.

CVE-2023-6374 has been assigned to this vulnerability. A CVSS v3.1 base score of 5.9 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N).

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 users take the following mitigation measures to minimize the risk of exploiting this vulnerability:

• Use a virtual private network (VPN), etc. to encrypt the communication between affected products and the peer.
• 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 to personal computers and network devices located in the LAN to which the affected products are connected.

For more information, see Mitsubishi Electric's security advisory.

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. This vulnerability has a high attack complexity.

5. UPDATE HISTORY

• January 30, 2024: Initial Publication