Grunt Attack: Exploiting Execution Dependencies in Microservices

Loosely-coupled and lightweight microservices running in containers are likely to form complex execution dependencies inside the system. The execution dependency arises when two execution paths partially share component microservices, resulting in potential runtime blocking effects. In this paper, we present Grunt Attack - a novel low-volume DDoS attack that takes advantage of the execution dependencies of microservice applications. Grunt Attack utilizes legitimate HTTP requests to accurately profile the internal pairwise dependencies of all supported execution paths in the target system. By grouping and characterizing all the execution paths based on their pairwise dependencies, the Grunt attacker can target only a few execution paths to launch a low-volume DDoS attack that achieves large performance damage to the entire system. To increase the attack stealthiness, the Grunt attacker avoids creating a persistent bottleneck by alternating the target execution paths within their dependency group. We validate the effectiveness of Grunt attack through experiments of open-source microservices benchmark applications on real clouds (e.g., EC2, Azure) equipped with state-of-the-art IDS/IPS systems and live attack scenarios. Our results show that Grunt attack consumes less than 20% additional CPU resource of the target system while increasing its average response time by over 10x.