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1. EXECUTIVE SUMMARY
- CVSS v3 7.5
- ATTENTION: Exploitable remotely/low attack complexity
- Vendor: Mitsubishi Electric
- Equipment: MELSEC iQ-R, Q and L Series
- Vulnerability: Uncontrolled Resource Consumption
2. UPDATE INFORMATION
This updated advisory is a follow-up to the advisory update ICSA-20-303-01 Mitsubishi Electric MELSEC iQ-R, Q and L Series (Update A) that was published May 18, 2021, to the ICS webpage on www.cisa.gov/uscert.
3. RISK EVALUATION
Successful exploitation of this vulnerability could cause a denial-of-service condition in the Ethernet port on the CPU module.
4. TECHNICAL DETAILS
4.1 AFFECTED PRODUCTS
The following versions of MELSEC iQ-R Series are affected:
- R 00/01/02 CPU, firmware Versions 20 and earlier
- R 04/08/16/32/120 (EN) CPU, firmware Versions 52 and earlier
- R 08/16/32/120 SFCPU, firmware Versions 22 and earlier
- R 08/16/32/120 PCPU, firmware Versions 25 and earlier
- R 16/32/64 MTCPU, all versions
The following versions of MELSEC Q Series are affected:
- Q03 UDECPU, Q 04/06/10/13/20/26/50/100 UDEHCPU, serial number 22081 and earlier
- Q 03/04/06/13/26 UDVCPU, serial number 22031 and earlier
- Q 04/06/13/26 UDPVCPU, serial number 22031 and earlier
- Q 172/173 DCPU-S1, all versions
- Q 172/173 DSCPU, all versions
- Q 170 MCPU, all versions
- Q 170 MSCPU (-S1), all versions
- MR-MQ100, all versions
The following versions of MELSEC L Series are affected:
--------- Begin Update B Part 1 of 1 ---------
- L 02/06/26 CPU (-P), L 26 CPU - (P) BT, serial number 23121 and earlier
--------- End Update B Part 1 of 1 ---------
4.2 VULNERABILITY OVERVIEW
The affected product is vulnerable to uncontrolled resource consumption in the MELSEC iQ-R, Q, and L Series CPU modules. When the CPU module receives a specially crafted packet from a malicious attacker, Ethernet communication may enter a denial-of-service condition and a reset is required to recover it.
- CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: Japan
Mitsubishi Electric reported this vulnerability to CISA.
Mitsubishi Electric recommends users take the following mitigation measures 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.
Please refer to Mitsubishi Electric’s website for details on available patches. Mitsubishi recommends users update their products by downloading and applying the latest versions. Please contact a Mitsubishi Electric representative for additional details.
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 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 this vulnerability.
For any questions related to this report, please contact the CISA at:
Toll Free: 1-888-282-0870
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