On a New Class of Pulsing Denial-of-Service Attacks and the Defense

In this paper we analyze a new class of pulsing denialof-service (PDoS) attacks that could seriously degrade the throughput of TCP flows. During a PDoS attack, periodic pulses of attack packets are sent to a victim. The magnitude of each pulse should be significant enough to cause packet losses. We describe two specific attack models according to the timing of the attack pulses with respect to the TCP’s congestion window movement: timeout-based and AIMD (additive-increasemultiplicative-decrease)-based. We show through an analysis that even a small number of attack pulses can cause significant throughput degradation. The second part of this paper is a novel two-stage scheme to detect PDoS attacks on a victim network. The first stage is based on a wavelet transform used to extract the desired frequency components of the data traffic and ACK traffic. The second stage is to detect change points in the extracted components. Through both simulation and testbed experiments, we verify the feasibility and effectiveness of the detection scheme.