Mitsubishi Electric MELSEC iQ-R Series (Update C)

1. EXECUTIVE SUMMARY

• CVSS v3 7.5
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Mitsubishi Electric
• Equipment: MELSEC iQ-R series
• Vulnerability: Uncontrolled Resource Consumption

2. UPDATE INFORMATION

This updated advisory is a follow-up to the advisory update titled ICSA-20-324-05 Mitsubishi Electric MELSEC iQ-R Series (Update B) that was published September 14, 2021 to the ICS webpage at www.cisa.gov/uscert.

3. RISK EVALUATION

Successful exploitation of this vulnerability could cause a denial-of-service condition for the affected product.

4. TECHNICAL DETAILS

4.1 AFFECTED PRODUCTS

Mitsubishi Electric reports the vulnerability affects the following MELSEC iQ-R series CPU module products: 

• R00/01/02CPU firmware Versions 19 and earlier
• R04/08/16/32/120(EN)CPU firmware Versions 51 and earlier
• R08/16/32/120SFCPU firmware Versions 22 and earlier
• R08/16/32/120PCPU firmware Versions 25 and earlier
• R08/16/32/120PSFCPU firmware Versions 06 and earlier
• RJ71EN71 firmware Versions 47 and earlier
• RJ71GF11-T2 firmware Versions 47 and earlier
• RJ72GF15-T2 firmware Versions 07 and earlier
• RJ71GP21-SX firmware Versions 47 and earlier
• RJ71GP21S-SX firmware Versions 47 and earlier

--------- Begin Update C Part 1 of 1 ---------

• RJ71C24(-R2/R4) all versions

--------- End Update C Part 1 of 1 ---------

• RJ71GN11-T2 firmware Versions 11 and earlier

4.2 VULNERABILITY OVERVIEW

4.2.1    UNCONTROLLED RESOURCE CONSUMPTION CWE-400

A vulnerability in MELSEC iQ-R series modules causes uncontrolled resource consumption. When a module receives a specially crafted SLMP packet from a malicious attacker, the program execution and communication could enter a denial-of-service condition.

CVE-2020-5668 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).

4.3 BACKGROUND

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

4.4 RESEARCHER

Xiaofei.Zhang reported this vulnerability to Mitsubishi Electric.

5. MITIGATIONS

Mitsubishi Electric has issued the following iQ-R Series firmware versions to address this issue:

• R00/01/02CPU: firmware Versions 20 or later
• R04/08/16/32/120 (EN) CPU: firmware Versions 52 or later
• R08/16/32/120SFCPU: firmware Versions 23 or later
• R08/16/32/120PCPU: firmware Versions 26 or later
• R08/16/32/120PSFCPU: firmware Versions 07 or later
• RJ71EN71: firmware Versions 48 or later
• RJ71GF11-T2: firmware Versions 48 or later
• RJ72GF15-T2: firmware Versions 08 or later
• RJ71GP21-SX: firmware Versions 48 or later
• RJ71GP21S-SX: firmware Versions 48 or later
• RJ71GN11-T2: firmware Versions 12 or later

For more information about this vulnerability and the associated mitigations, please see the vulnerability information on the Mitsubishi website.

Mitsubishi Electric also recommends the following practices to minimize the risk of 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.

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.

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.