Date of Award


Document Type


Degree Name

Master of Science


Department of Electrical and Computer Engineering

First Advisor

Barry E. Mullins, PhD.


Industrial control systems (ICS) are designed to be resilient, capable of recovering from process faults and failures with limited impact to operations. Current ICS resiliency strategies use redundant PLCs. However, these redundant PLCs, being of similar make and model, can be exploited by the same cyber attack, defeating the ICS's resiliency strategy. This research proposes a resiliency strategy for ICS that employs an active defense technique to remove the cyber common cause failure. The resiliency of the active defense strategy is compared to traditional ICS resiliency by implementing both strategies in a semi-simulated wastewater treatment plant aeration basin that experiences a cyber attack. The active defense technique was shown to maintain effective treatment of the wastewater through the cyber attack where the traditional implementation allowed a process disruption that prevented the effective treatment of the wastewater.

AFIT Designator


DTIC Accession Number