Mitsubishi Electric MELSOFT GT OPC UA

1. EXECUTIVE SUMMARY

• CVSS v3 7.5
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Mitsubishi Electric
• Equipment: MELSOFT GT OPC UA Client
• Vulnerabilities: Out-of-bounds Read, Integer Overflow or Wraparound

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow a remote attacker to send specially crafted messages, resulting in information disclosure or a denial-of-service condition.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following products and version combinations using OPC UA Client Connections are affected:

• MELSOFT GT OPC UA Client: Versions 1.00A to 1.02C
• GT SoftGOT2000: Versions 1.215Z to 1.270G

3.2 VULNERABILITY OVERVIEW

3.2.1    OUT-OF-BOUNDS READ CWE-125

The affected product is vulnerable due to an out-of-bounds read, which may allow an attacker to send specially crafted messages to disclose information on memory or cause a denial-of-service condition.

CVE-2021-3712 has been assigned to this vulnerability. A CVSS v3 base score of 7.4 has been assigned; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H).

3.2.2    INTEGER OVERFLOW OR WRAPAROUND CWE-190

The affected product is vulnerable due to an integer overflow, which may allow an attacker to cause a denial-of-service condition.

CVE-2021-23840 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/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

Mitsubishi Electric reported these vulnerabilities to CISA.

4. MITIGATIONS

Mitsubishi Electric recommends users update software to the latest versions below. Users will need to contact a Mitsubishi representative to obtain the updates:

• MELSOFT GT OPC UA Client: Update to 1.03D or later
• GT SoftGOT2000: Update to 1.275M or later

Mitsubishi Electric recommends users take the following mitigations to minimize the risk of exploiting these vulnerabilities:

• When connecting the products to the Internet, use a virtual private network (VPN, etc.) to prevent spoofing and sniffing.
• Use the products within the LAN and block access from untrusted networks and hosts.
• Update the OPC UA server to the latest version.
• Install antivirus software.
• Restrict physical access to computers and network equipment that use the affected products.

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 they are not accessible from the Internet.
• Locate control system networks and remote devices behind firewalls and isolate them from the business network.
• When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its connected devices.

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 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 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 these vulnerabilities. 

• Mitsubishi Electric