Can attacks reduce Age of Information?

We study a monitoring system in which a single source sends status updates to a monitor through a communication channel. The communication channel is modeled as a queueing system, and we assume that attacks occur following a random process. When an attack occurs, all packets in the queueing system are discarded. While one might expect attacks to always negatively impact system performance, we demonstrate in this paper that, from the perspective of Age of Information (AoI), attacks can in some cases reduce the AoI. Our objective is to identify the conditions under which AoI is reduced and to determine the attack rate that minimizes or reduces AoI. First, we analyze single and tandem M/M/1/1 queues with preemption and show that attacks cannot reduce AoI in these cases. Next, we examine a single M/M/1/1 queue without preemption and establish necessary and sufficient conditions for the existence of an attack rate that minimizes AoI. For this scenario, we also derive an upper bound for the optimal attack rate and prove that it becomes tight when the arrival rate of updates is very high. Through numerical experiments, we observe that attacks can reduce AoI in tandem M/M/1/1 queues without preemption, as well as in preemptive M/M/1/2 and M/M/1/3 queues. Furthermore, we show that the benefit of attacks on AoI increases with the buffer size.