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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-20-324-05) Mitsubishi Electric MELSEC iQ-R Series
20 November 2020
AusCERT Security Bulletin Summary
Product: Mitsubishi Electric MELSEC iQ-R series
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2020-5668
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ICS Advisory (ICSA-20-324-05)
Mitsubishi Electric MELSEC iQ-R Series
Original release date: November 19, 2020
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For more information about TLP, see https://us-cert.cisa.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 7.5
o ATTENTION: Exploitable remotely/low skill to exploit
o Vendor: Mitsubishi Electric
o Equipment: MELSEC iQ-R series
o Vulnerability: Uncontrolled Resource Consumption
2. RISK EVALUATION
Successful exploitation of this vulnerability could cause a denial-of-service
condition for the affected product.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Mitsubishi Electric reports the vulnerability affects the following MELSEC iQ-R
series CPU module products:
o R00/01/02CPU firmware Versions 19 and earlier
o R04/08/16/32/120(EN)CPU firmware Versions 51 and earlier
o R08/16/32/120SFCPU firmware Versions 22 and earlier
o R08/16/32/120PCPU all versions
o R08/16/32/120PSFCPU all versions
o RJ71EN71 firmware Versions 47 and earlier
o RJ71GF11-T2 firmware Versions 47 and earlier
o RJ72GF15-T2 firmware Versions 07 and earlier
o RJ71GP21-SX firmware Versions 47 and earlier
o RJ71GP21S-SX firmware Versions 47 and earlier
o RJ71C24(-R2/R4) all versions
o RJ71GN11-T2 all versions
3.2 VULNERABILITY OVERVIEW
3.2.1 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
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/
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Japan
Xiaofei.Zhang reported this vulnerability to Mitsubishi Electric.
Mitsubishi Electric has issued the following iQ-R Series firmware versions to
address this issue:
o R00/01/02CPU: firmware Versions 20 or later
o R04/08/16/32/120 (EN) CPU: firmware Versions 52 or later
o R08/16/32/120SFCPU: firmware Versions 23 or later
o RJ71EN71: firmware Versions 48 or later
o RJ71GF11-T2: firmware Versions 48 or later
o RJ72GF15-T2: firmware Versions 08 or later
o RJ71GP21-SX: firmware Versions 48 or later
o RJ71GP21S-SX: firmware Versions 48 or later
Mitsubishi Electric also recommends the following practices to minimize the
risk of exploiting this vulnerability:
o Use a firewall or virtual private network (VPN), etc., to prevent
unauthorized access when Internet access is required.
o Use within a LAN and block access from untrusted networks and hosts through
For more information about this vulnerability and the associated mitigations,
please see the vulnerability information on the Mitsubishi website .
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
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.
For any questions related to this report, please contact the CISA at:
Toll Free: 1-888-282-0870
CISA continuously strives to improve its products and services. You can help by
choosing one of the links below to provide feedback about this product.
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