ICS-CERT has released an advisory on a Rockwell Automation Allen-Bradley MicroLogix 1400 Controllers vulnerability. Multiple versions of this product 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. ICS-CERT also recommends a series of defensive measures to minimize the risk of exploitation of this vulnerability. ICS-CERT.