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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-22-013-07) 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
CVE Names: CVE-2021-20613
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ICS Advisory (ICSA-22-013-07)
Mitsubishi Electric MELSEC-F Series
Original release date: January 13, 2022
All information products included in https://us-cert.cisa.gov/ics are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
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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: Improper Initialization
2. RISK EVALUATION
Successful exploitation of this vulnerability may cause a denial-of-service
condition in the affected product.
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 1.16 and prior
o FX3U-ENET-L: Firmware Version 1.16 and prior
o FX3U-ENET-P502: Firmware Version 1.16 and prior
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER INITIALIZATION CWE-665
An attacker could send a specially crafted packet that could create a
denial-of-service condition in the communication function of the product. A
system reset is required for recovery.
CVE-2021-20613 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
Mitsubishi Electric reported this vulnerability to CISA.
Mitsubishi Electric corrected this vulnerability in the following products and
versions, as follows:
o FX3U-ENET: Firmware Version 1.17 or later
o FX3U-ENET-L: Firmware Version 1.17 or later
o FX3U-ENET-P502: Firmware Version 1.17 or later
Mitsubishi Electric also recommends users take the following mitigation
measures to minimize the risk of exploiting this vulnerability:
o Use a firewall, VPN, or other barrier to prevent unauthorized access when
Internet access is required.
o Use within a LAN and block access from untrusted networks and hosts through
For specific update instructions and additional details see the Mitsubishi
Electric advisory .
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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