Security of Control Systems with Erroneous Observations

Abstract

We address the problem of security of stochastic control systems when observation measurements used to close the control loop may be erroneous, due to a malicious adversary who has intercepted the associated sensors or the communication network. We show how the method of dynamic watermarking can be employed to secure such a system. This is a method of defense based on stochastic considerations, relying on the inability of the attacker to separate the ambient noise present in the system from a deliberatively superimposed random watermark. We present the results of experiments against several attacks, and show the capability of this method to detect attacks in all the tested cases. The experiments are conducted on a prototypical process control system consisting of two coupled water tanks.