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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-22-013-01) Mitsubishi Electric MELSEC-F Series
14 January 2022
AusCERT Security Bulletin Summary
Product: Mitsubishi Electric MELSEC-F Series
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
Reduced Security -- Remote/Unauthenticated
CVE Names: CVE-2021-20612
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ICS Advisory (ICSA-22-013-01)
Mitsubishi Electric MELSEC-F Series
Original release date: January 13, 2022
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1. EXECUTIVE SUMMARY
o CVSS v3 7.5
o ATTENTION: Exploitable remotely/low attack complexity
o Vendor: Mitsubishi Electric
o Equipment: MELSEC-F Series
o Vulnerability: Lack of Administrator Control Over Security
2. RISK EVALUATION
Successful exploitation of this vulnerability could lead to a denial-of-service
condition or cause other unspecified effects in the communication function of
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of MELSEC-F Series with FX3U-ENET, an Ethernet-Internet
block, are affected:
o FX3U-ENET Firmware Version 1.14 and prior
o FX3U-ENET-L Firmware Version 1.14 and prior
o FX3U-ENET-P502 Firmware Version 1.14 and prior
3.2 VULNERABILITY OVERVIEW
3.2.1 LACK OF ADMINISTRATOR CONTROL OVER SECURITY CWE-671
The affected product is vulnerable due to a lack of administrative controls,
which may allow an attacker to remotely send specially crafted packets and
cause a denial-of-service condition or other unspecified effects.
CVE-2021-20612 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/
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Japan
Mitsubishi Electric reported this vulnerability to CISA.
Mitsubishi Electric corrected this vulnerability in the following products and
o FX3U-ENET: Firmware Version 1.16 or later
o FX3U-ENET-L: Firmware Version 1.16 or later
o FX3U-ENET-P502: Firmware Version 1.16 or later
Mitsubishi Electric recommends users to take the following mitigations:
o Use a firewall or virtual private network (VPN) to prevent unauthorized
access when Internet access is required.
o Use within a LAN and block access from untrusted networks and hosts through
Please contact Mitsubishi Electric Support for assistance and review the
Mitsubishi Electric security advisory for more information about this issue.
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
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
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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