ICS Advisory (ICSA-17-138-03)

Rockwell Automation MicroLogix 1100 Controllers

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CVSS v3 7.5

Vendor: Rockwell Automation

Equipment: MicroLogix 1100 Controllers

Vulnerability: Improper Input Validation


This advisory was originally posted to the NCCIC Portal on May 18, 2017, and is being released to the NCCIC/ICS-CERT web site.


The following versions of MicroLogix 1100 controllers are affected:

  • 1763-L16BWA,
  • 1763-L16AWA,
  • 1763-L16BBB, and
  • 1763-L16DWD.


Successful exploitation of this vulnerability could cause the device that the attacker is accessing to enter a Denial-of-Service (DoS) condition.


Rockwell Automation recommends updating to the latest firmware revision of MicroLogix 1100 controllers, Version FRN 16.0 or later, which is available at the following location:


For more information on this vulnerability and more detailed mitigation instructions, please see Rockwell Automation’s advisory at the following location:


As well as Rockwell Automation’s security page:


ICS-CERT and Rockwell Automation recommend that users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:

  • Block all traffic to EtherNet/IP or other CIP protocol-based devices from outside the Manufacturing Zone by blocking or restricting access to Port 2222/TCP and UDP and Port 44818/TCP and UDP 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 Rockwell Automation’s Knowledgebase Article ID 898270 which is available at the following location:


  • Minimize network exposure for all control system devices and/or systems, and help confirm that they are not accessible from the Internet.
  • Locate control system networks and devices behind firewalls, and use best practices when isolating them from the business network. The Common Plant-wide Ethernet (CPwE) guide provides recommendations for deploying a plant-wide architecture: Industrial Firewalls within a CPwE Architecture
  • 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. Not remotely exploitable. High skill level is needed to exploit.


A remote, unauthenticated attacker could send a single, specially crafted Programmable Controller Communication Commands (PCCC) packet to the controller that could potentially cause the controller to enter a DoS condition.

CVE-2017-7924 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).


Mark Gondree of Sonoma State University, Francisco Tacliad and Thuy Nguyen of the Naval Postgraduate School reported this vulnerability.


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

Countries/Areas Deployed: Worldwide

Company Headquarters Location: Milwaukee, Wisconsin

Contact Information

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

Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  https://us-cert.cisa.gov/ics 
or incident reporting:  https://us-cert.cisa.gov/report

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