ICS Advisory (ICSA-21-049-02)

Mitsubishi Electric FA engineering software products

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  • CVSS v3 7.5
  • ATTENTION: Exploitable remotely/low skill level to exploit
  • Vendor: Mitsubishi Electric
  • Equipment: FA engineering software products
  • Vulnerabilities: Heap-based Buffer Overflow, Improper Handling of Length Parameter Inconsistency


Successful exploitation of these vulnerabilities may cause a denial-of-service condition. 



Mitsubishi Electric reports these vulnerabilities affect the following FA engineering software products that communicate with MELSEC, FREQROL, or GOT products: 

  • C Controller module setting and monitoring tool, all versions
  • CPU Module Logging Configuration Tool, all versions
  • CW Configurator, all versions
  • Data Transfer, all versions
  • EZSocket, all versions
  • FR Configurator, all versions
  • FR Configurator SW3, all versions
  • FR Configurator2, all versions
  • GT Designer3 Version1(GOT1000), all versions
  • GT Designer3 Version1(GOT2000), all versions
  • GT SoftGOT1000 Version3, all versions
  • GT SoftGOT2000 Version1, all versions
  • GX Configurator-DP, Versions 7.14Q and prior
  • GX Configurator-QP, all versions
  • GX Developer, all versions
  • GX Explorer, all versions
  • GX IEC Developer, all versions
  • GX LogViewer, all versions
  • GX RemoteService-I, all versions
  • GX Works2, Versions 1.597X and prior
  • GX Works3, Versions 1.070Y and prior
  • M_CommDTM-HART, all versions
  • M_CommDTM-IO-Link, all versions
  • MELFA-Works, all versions
  • MELSEC WinCPU Setting Utility, all versions
  • MELSOFT EM Software Development Kit (EM Configurator), all versions
  • MELSOFT Navigator, all versions
  • MH11 SettingTool Version2, all versions
  • MI Configurator, all versions
  • MT Works2, all versions
  • MX Component, all versions
  • Network Interface Board CC IE Control utility, all versions
  • Network Interface Board CC IE Field Utility, all versions
  • Network Interface Board CC-Link Ver.2 Utility, all versions
  • Network Interface Board MNETH utility, all versions
  • PX Developer, all versions
  • RT ToolBox2, all versions
  • RT ToolBox3, all versions
  • Setting/monitoring tools for the C Controller module, all versions
  • SLMP Data Collector, all versions



A malicious attacker may cause a denial-of-service condition by spoofing MELSEC, GOT, or FREQROL, and returning crafted reply packets. 

CVE-2021-20587 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:N/A:H).


A malicious attacker may cause a denial-of-service condition by spoofing MELSEC, GOT, or FREQROL, and returning crafted reply packets. 

CVE-2021-20588 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:N/A:H).




dliangfun reported these vulnerabilities to Mitsubishi Electric.


Mitsubishi Electric recommends that users download and update the latest version of each software product:

  • GX Configurator-DP, Version 7.15R or later
  • GX Works2, Version 1.600A or later
  • GX Works3, Version 1.072A or later

Mitsubishi Electric recommends users who are using a product that has not released a fixed version or who cannot immediately update the product, take the following mitigations to minimize risk:

  • Install the fixed version of GX Works3 on the computer running the products when communicating with MELSEC. Fixed software products that communicate with GOT and FREQROL are currently under development. GX Works3 provides comprehensive countermeasures that deliver the same countermeasures to other products.
  • Operate the products under an account that does not have administrator's privileges.
  • Install antivirus software in the computer running the products.
  • Restrict network exposure for all control system devices or systems to the minimum necessary, and ensure they are not accessible from untrusted networks and hosts.
  • Locate control system networks and remote devices behind firewalls and isolate them from the business network.
  • Use virtual private network (VPN) when remote access is required.

Please refer to the Mitsubishi Electric advisory for details on how to check firmware version.

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 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 these vulnerabilities. 

Contact Information

For any questions related to this report, please contact the CISA at:

Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  https://us-cert.cisa.gov/ics 
or incident reporting:  https://us-cert.cisa.gov/report

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