Timing is Almost Everything: Realistic Evaluation of the Very Short Intermittent DDoS Attacks

Distributed Denial-of-Service (DDoS) is a big threat to the security and stability of Internet-based services today. Among the recent advanced application-layer DDoS attacks, the Very Short Intermittent DDoS (VSI-DDoS) is the attack, which can bypass existing detection systems and significantly degrade the QoS experienced by users of web services. However, in order for the VSI-DDoS attack to work effectively, bots participating in the attack should be tightly synchronized, an assumption that is difficult to be met in reality. In this paper, we conducted a quantitative analysis to understand how a minimal deviation from perfect synchronization in botnets affects the performance and effectiveness of the VSI-DDoS attack. We found that VSI-DDoS became substantially less effective. That is, it lost 85.7% in terms of effectiveness under about 90ms synchronization inaccuracy, which is a very small inaccuracy under normal network conditions.