Detecting Cache Pollution Attacks Using Bloom Filter

Abstract

To provide web browsing and video streaming services with desirable quality, cache servers have been widely used to deliver digital data to users from locations close to users. For example, in the MEC (mobile edge computing), cache memories are provided at base stations of 5G cellular networks to reduce the traffic load in the backhaul networks. Cache servers are also connected to many edge routers in the CDN (content delivery network), and they are provided at routers in the ICN (information-centric networking). However, the cache pollution attack (CPA) which degrades the cache hit ratio by intentionally sending many requests to non-popular contents will be a serious threat in the cache networks. Quickly detecting the CPA hosts and protecting the cache servers is important to effectively utilize the cache resources. Therefore, in this paper, we propose a method of accurately detecting the CPA hosts using a limited amount of memory resources. The proposed method is based on a Bloom filter using the combination of identifiers of host and content as keys. We also propose to use two Bloom filters in parallel to continuously detect CPA hosts. Through numerical evaluations, we show that the proposed method suppresses the degradation of the cache hit ratio caused by the CPA while avoiding the false identification of legitimate hosts.