Leveraging Prefix Structure to Detect Volumetric DDoS Attack Signatures with Programmable Switches

As increasingly complex and dynamic volumetric DDoS attacks continue to wreak havoc on edge networks, two recent developments promise to bolster DDoS defense at the edge. First, programmable switches have emerged as promising means for achieving scalable and cost-effective attack signature detection. However, their practical application in edge networks remains a challenging open problem. Second, machine learning (ML)-based solutions have demonstrated potential in accurately detecting attack signatures based on per-flow traffic features. Yet, their inability to effectively scale to the traffic volumes and number of flows in actual production edge networks has largely excluded them from practical considerations.In this paper, we introduce ZAPDOS, a novel approach to accurately, quickly, and scalably detect volumetric DDoS attack signatures at the source prefix level. ZAPDOS is the first to utilize a key characteristic of the observed structure of measured attack and benign source prefixes (i.e., a pronounced cluster-within-cluster property) and effectively apply it in practice against modern attacks. ZAPDOS operates by monitoring aggregate prefix-level features in switch hardware, employing a learning model to identify prefixes suspected of containing attack sources, and using several innovative algorithmic methods to pinpoint attack sources efficiently. We have built a hardware prototype of ZAPDOS and a packet-level software simulator which achieve comparable accuracy results. Since existing datasets are inadequate for training and evaluating prefix-level models, we have developed a new data-fusion methodology for training and evaluating ZAPDOS. We use our prototype and simulator to show that ZAPDOS can detect volumetric DDoS attack signatures with orders of magnitude lower error rates than state-of-the-art under comparable monitoring resource budgets and for a range of different attack scenarios.