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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-19-311-01) Mitsubishi Electric MELSEC-Q
Series and MELSEC-L Series CPU Modules
8 November 2019
AusCERT Security Bulletin Summary
Product: Mitsubishi Electric MELSEC-Q Series and MELSEC-L Series CPU
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2019-13555
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ICS Advisory (ICSA-19-311-01)
Mitsubishi Electric MELSEC-Q Series and MELSEC-L Series CPU Modules
Original release date: November 07, 2019
All information products included in http://ics-cert.us-cert.gov 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 contained within. DHS does not endorse any commercial product or
service, referenced in this product or otherwise. Further dissemination of this
product is governed by the Traffic Light Protocol (TLP) marking in the header.
For more information about TLP, see http://www.us-cert.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 7.5
o ATTENTION: Exploitable remotely/low skill level to exploit
o Vendor: Mitsubishi Electric
o Equipment: MELSEC-Q Series and MELSEC-L Series CPU Modules
o Vulnerability: Uncontrolled Resource Consumption
2. RISK EVALUATION
Successful exploitation of this vulnerability may prevent the FTP client from
connecting to the FTP server on MELSEC-Q Series and MELSEC-L Series CPU module.
Only FTP server function is affected by this vulnerability.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of MELSEC-Q Series and MELSEC-L Series CPU modules are
o [MELSEC-Q Series]
Q03/04/06/13/26UDVCPU: serial number 21081 and prior,
Q04/06/13/26UDPVCPU: serial number 21081 and prior, and
Q03UDECPU, Q04/06/10/13/20/26/50/100UDEHCPU: serial number 21081 and
o [MELSEC-L Series]
L02/06/26CPU, L26CPU-BT: serial number 21101 and prior,
L02/06/26CPU-P, L26CPU-PBT: serial number 21101 and prior, and
L02/06/26CPU-CM, L26CPU-BT-CM: serial number 21101 and prior.
3.2 VULNERABILITY OVERVIEW
3.2.1 UNCONTROLLED RESOURCE CONSUMPTION CWE-400
A remote attacker can cause the FTP service to enter a denial-of-service
condition dependent on the timing at which a remote attacker connects to the
FTP server on the above CPU modules.
CVE-2019-13555 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
Tri Quach of Amazon's Customer Fulfillment Technology Security (CFTS) group
reported this vulnerability to CISA.
Mitsubishi Electric has produced a new version of the firmware. Additional
information about this vulnerability or Mitsubishi Electric's compensating
control is available by contacting a local Mitsubishi Electric representative,
which can be found at the following location:
Mitsubishi Electric strongly recommends that users should operate the affected
device behind a firewall.
CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:
o Minimize network exposure for all control system devices and/or systems,
and ensure that they are not accessible from the Internet .
o Locate control system networks and remote devices behind firewalls, and
isolate them from the business network.
o When remote access is required, use secure methods, such as Virtual Private
Networks (VPNs), recognizing that VPNs may have vulnerabilities and should
be updated to the most current version available. Also recognize that VPN
is only as secure as the connected devices.
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.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.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.
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