How to Attack and Congest Delay-Sensitive Applications on the Cloud

The delay and service-blocking experienced by users are critical measures of quality of service in real-time distributed systems. Attacks directed at such facilities aim at disrupting the service and hurting these metrics. Our goal is to characterize worst-case attacks on such systems.We use queueing models to study attackers who wish to maximize damage while constrained by attack resources. A key question pertaining to systems design is whether a damage maximizing attack should focus on heavily affecting a small number of facilities or spread its efforts over many facilities.We analyze attacks which damage the system resources (i.e., Capacity attacks) and show that optimal capacity attacks are concentrated. We further use a Max-Min (attacker and defender) analysis where the defender can migrate requests in response to the attack: An intriguing result is that under certain conditions an optimal attack will spread its efforts over many sites. This is in contrast to the attack concentration predictions of (agnostic to queueing delays) prior studies.We also address DDoS (or Flow) attacks where attackers create loads of dummy requests and send them to the system. We prove that concentrating the attack efforts is always the optimal strategy, regardless of whether the system reacts by migrating requests, in contrast to the capacity attacks.