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AUSCERT External Security Bulletin Redistribution
ICS Advisory (ICSA-20-063-03)
4 March 2020
AusCERT Security Bulletin Summary
Product: Omron PLC CJ
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2020-6986
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ICS Advisory (ICSA-20-063-03)
Omron PLC CJ Series
Original release date: March 03, 2020
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1. EXECUTIVE SUMMARY
o CVSS v3 7.5
o ATTENTION: Exploitable remotely/low skill level to exploit
o Vendor: Omron
o Equipment: PLC CJ Series
o Vulnerability: Uncontrolled Resource Consumption
2. RISK EVALUATION
Successful exploitation of this vulnerability could cause a denial-of-service
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of Omron programmable logic controllers are affected:
o Omron PLC CJ series, all versions
3.2 VULNERABILITY OVERVIEW
3.2.1 UNCONTROLLED RESOURCE CONSUMPTION CWE-400
An attacker can send a series of specific data packets within a short period,
causing a service error on the PLC Ethernet module, which in turn causes a PLC
service denied result.
CVE-2020-6986 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
Jipeng You (XDU) reported this vulnerability to CISA.
Omron recommends the following mitigation measures:
o Filter FINS port: Protect access to Omron's PLC with a firewall and by
blocking unnecessary remote access to FINS port (default: 9600).
o Filter IP addresses: Protect access to Omron's PLC with a firewall and
filtering devices connected to the PLC by IP address.
For more information on Omron PLC CJ Series vulnerabilities, refer to
Vulnerabilities in Omron CJ series CPU PLCs .
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.
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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