Mitsubishi Electric GOT2000 series and GT SoftGOT2000

1. EXECUTIVE SUMMARY

• CVSS v3 5.9 ***ATTENTION: **Exploitable remotely
• Vendor: Mitsubishi Electric
• Equipment: GOT2000 series and GT SoftGOT2000
• **Vulnerability:**Missing Synchronization

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker to cause a denial-of-service condition.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Mitsubishi Electric reports this vulnerability affects the MODBUS/TCP slave communication function of following products:

• GOT2000 models GT27, GT25, GT23: All communication driver versions between 01.19.000 and 01.39.010. These versions are affected when using the “MODBUS/TCP Slave, Gateway” communication driver.
• GT SoftGOT2000: All versions between 1.170C and 1.256S. These versions are affected when configured to use “MODBUS/TCP Slave” communication.

3.2 VULNERABILITY OVERVIEW

3.2.1 MISSING SYNCHRONIZATION CWE-820

A malicious attacker can stop the communication function of products by rapidly and repeatedly connecting and disconnecting to and from the MODBUS/TCP communication port on GOT, which may cause a denial-of-service condition. Restart of hardware and software is required to recover.

CVE-2021-20592 has been assigned to this vulnerability. A CVSS v3 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:N/A:H).

3.3 BACKGROUND

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

3.4 RESEARCHER

Parul Sindhwad and Dr. Faruk Kazi of COE-CNDS Lab, VJTI reported this vulnerability to CISA.

4. MITIGATIONS

Mitsubishi Electric recommends users upgrade to the following versions:

• GOT2000 models GT27, GT25, GT23: Update communication driver to version 01.40.000 or later (Fixed communication driver is included in GT Designer3 Version1(GOT2000) Version 1.260W or later)
• GT SoftGOT2000: Update to Version 1.26W or later

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

Mitsubishi Electric recommends users take the following mitigations to minimize the risk of this vulnerability:

• When connecting the products to the Internet, use a firewall or virtual private network (VPN), etc. to prevent unauthorized access.
• Use the products within the LAN and block access from untrusted networks and hosts.
• Install antivirus software on your computer that can access the product.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:

• Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from the Internet.

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 us-cert.cisa.gov. Several recommended 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 on us-cert.cisa.gov in the Technical Information Paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to CISA for tracking and correlation against other incidents.

No known public exploits specifically target this vulnerability. This vulnerability has a high attack complexity.