ESB-2018.0108 - [Appliance] Rockwell Automation Allen-Bradley MicroLogix 1400 Controllers: Multiple vulnerabilities 2018-01-10

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             AUSCERT External Security Bulletin Redistribution

        A vulnerability has been identified in Rockwell Automation
                 Allen-Bradley MicroLogix 1400 Controllers
                              10 January 2018


        AusCERT Security Bulletin Summary

Product:           Rockwell Automation Allen-Bradley MicroLogix 1400 Controllers
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                   Denial of Service               -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2017-16740  

Original Bulletin:

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Advisory (ICSA-18-009-01)

Rockwell Automation Allen-Bradley MicroLogix 1400 Controllers

Original release date: January 09, 2018

Legal Notice

All information products included in 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

CVSS v3 8.6

ATTENTION: Remotely exploitable/low skill level to exploit.

Vendor: Rockwell Automation

Equipment: Allen-Bradley MicroLogix 1400 Controllers

Vulnerability: Buffer Overflow


The following versions of MicroLogix 1400 Controllers, a PLC, are affected:

MicroLogix 1400 Controllers, Series B and C Versions 21.002 and earlier

Rockwell Automation reports that the following catalogs are affected:








Successful exploitation of this vulnerability could cause the device that the
attacker is accessing to become unresponsive to Modbus TCP communications and
affect the availability of the device.


Rockwell Automation encourages affected users to upgrade to the latest version
of available firmware, FRN 21.003, which can be obtained from:
(link is external)

Rockwell Automation also suggests that Modbus TCP can be disabled if it is not
necessary in the implementation of the device to mitigate the vulnerability.

For more information, Rockwell Automation has released a security bulletin 
that can be accessed using valid credentials at: (link
is external)

NCCIC/ICS-CERT recommends that users take defensive measures to minimize the 
risk of exploitation of this vulnerability. Specifically, users should:

Minimize network exposure for all control system devices and/or systems, and 
ensure that they are not accessible from the Internet.

Locate control system networks and remote devices behind firewalls, and 
isolate them from the business network.

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.

ICS-CERT reminds organizations to perform proper impact analysis and risk 
assessment prior to deploying defensive measures.

ICS-CERT also provides a section for control systems security recommended 
practices on the ICS-CERT web page. 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 in the ICS-CERT Technical Information Paper, 
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation 
Strategies, that is available for download from the ICS-CERT web site.

Organizations observing any suspected malicious activity should follow their 
established internal procedures and report their findings to ICS-CERT for 
tracking and correlation against other incidents.

No known public exploits specifically target this vulnerability.



The stack-based buffer overflow vulnerability has been identified, which may 
allow remote code execution.

CVE-2017-16740 has been assigned to this vulnerability. A CVSS v3 base score 
of 8.6 has been assigned; the CVSS vector string is 


Thiago Alves of the University of Alabama reported the vulnerability to 
Rockwell Automation and ICS-CERT.


Critical Infrastructure Sector(s): Critical Manufacturing, Food and 
Agriculture, and Water and Wastewater Systems.

Countries/Areas Deployed: Worldwide

Company Headquarters Location: Wisconsin

Contact Information

For any questions related to this report, please contact the NCCIC at:

Email: (link sends e-mail)

Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:

or incident reporting:

The NCCIC continuously strives to improve its products and services. You can 
help by choosing one of the links below to provide feedback about this 

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