-----BEGIN PGP SIGNED MESSAGE-----
AUSCERT External Security Bulletin Redistribution
Advisory (icsa-21-189-01) Rockwell Automation MicroLogix 1100
9 July 2021
AusCERT Security Bulletin Summary
Product: Rockwell Automation MicroLogix 1100
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2021-33012
- --------------------------BEGIN INCLUDED TEXT--------------------
ICS Advisory (ICSA-21-189-01)
Rockwell Automation MicroLogix 1100
Original release date: July 08, 2021
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
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 https://us-cert.cisa.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 8.6
o ATTENTION: Exploitable remotely/low attack complexity
o Vendor: Rockwell Automation
o Equipment: MicroLogix 1100
o Vulnerability: Improper Input Validation
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to create
a denial-of-service condition.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Rockwell Automation reports the vulnerability affects the following products:
o MicroLogix 1100: All versions
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER INPUT VALIDATION CWE-20
A remote, unauthenticated attacker sending specially crafted commands could
cause the PLC to fault when the controller is switched to RUN mode, which
results in a denial-of-service condition. If successfully exploited, this
vulnerability will cause the controller to fault when the controller is
switched to RUN mode.
CVE-2021-33012 has been assigned to this vulnerability. A CVSS v3 base score of
8.6 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:C/
o CRITICAL INFRASTRUCTURE SECTORS: Chemical, Critical Manufacturing, Food and
Agriculture, Water and Wastewater Systems
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: United States
Beau Taub of Bayshore Networks reported this vulnerability to Rockwell
A controller in this fault state can be recovered by downloading a new project
or an offline copy of the project to the controller. Rockwell Automation
recommends users set the controller switch to RUN mode to prevent remote
programming. Users are encouraged to have a backup copy of the project in the
case it is necessary to recover from an event. Rockwell Automation also
recommends users should consider migrating to the Micro870 controller.
Rockwell automation recommends the following general security guidelines:
o Utilize proper network infrastructure controls, such as firewalls, to help
ensure EtherNet/IP traffic from unauthorized sources are blocked.
o Consult the product documentation for specific features, such as a hardware
mode switch setting, to which may be used to block unauthorized changes,
o Block all traffic to EtherNet/IP or other CIP protocol-based devices from
outside the Manufacturing Zone by blocking or restricting access to TCP and
UDP Port 2222 and Port 44818 using proper network infrastructure controls,
such as firewalls, UTM devices, or other security appliances. For more
information on TCP/UDP ports used by Rockwell Automation Products, see
Knowledge Base Article BF7490
o Use trusted software, software patches, antivirus/antimalware programs and
interact only with trusted websites and attachments.
o Minimize network exposure for all control system devices and/or systems and
ensure they are not accessible from the Internet. For further information
about the risks of unprotected Internet accessible control systems, please
see Knowledgebase Article PN715
o Locate control system networks and 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.
Rockwell Automation users can refer to the Converged Plantwide Ethernet (CPwE)
Design and Implementation Guide for best practices for deploying network
segmentation and broader defense in depth strategies. Users can also refer to
the Rockwell Automation System Security Design Guidelines on how to use
Rockwell Automation products to improve the security of their industrial
For more information see Rockwell Automation's Security advisory (Login
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.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 us-cert.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.
- --------------------------END INCLUDED TEXT--------------------
You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to email@example.com
and we will forward your request to the appropriate person.
NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.
NOTE: This is only the original release of the security bulletin. It may
not be updated when updates to the original are made. If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.
Contact information for the authors of the original document is included
in the Security Bulletin above. If you have any questions or need further
information, please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
Australian Computer Emergency Response Team
The University of Queensland
Internet Email: firstname.lastname@example.org
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for member emergencies only.
-----BEGIN PGP SIGNATURE-----
-----END PGP SIGNATURE-----