Exploring the behaviors and threats of pollution attack in cooperative MEC caching

The cooperative Mobile Edge Computing (MEC) caching, where caches are distributed in 5G edge to cooperatively bring popular contents closer to mobile users, is concocted with high expectation on improving users' quality of experience. However, the system may suffer severely from the pollution attack. By frequently requesting unpopular contents, the adversaries in the pollution attack can break the patterns of content popularity. As a result, the cooperative content placement decision making, which relies on the popularity pattern, will be misguided to store unpopular contents instead of popular ones. In this paper, we explore the behaviors and threats of pollution attack in cooperative MEC caching. Starting with single-inject pollution where adversaries concentrate the attack on a single cache, we study the behaviors and diffusion features from both statistical experiments and theoretical analysis. Results show that the unpopular contents can fill into caches within 2 hops from attackers, and caches within 3 hops suffer from severe damage. Meanwhile, we also derive the upper boundary of the attack damage and present a boundary analysis. Furthermore, in multiple-inject pollution where the adversaries launch multiple single-inject pollution simultaneously, we evaluate the threat when attackers intelligently organize the attacks. It is found that the adversaries can cause 44% severer damage and cover 45% more area after intelligently organizing the attacks. Our work in this paper provides a fundamental basis for countermeasures designing.