A belief propagation approach for detecting shilling attacks in collaborative filtering

Abstract

Recommender systems have been widely used in e-commerce websites to suggest items that meet users' preferences. Collaborative filtering, which is the most popular recommendation algorithm, is vulnerable to shilling attacks, where a group of spam users collaborate to manipulate the recommendations. Several attack detection algorithms have been developed to detect spam users and remove them from the system. However, the existing algorithms focus mostly on rating patterns of users. In this paper, we develop a probabilistic inference framework that further exploits the target items for attack detection. In addition, the user features can also be conveniently incorporated in this framework. We utilize the Belief Propagation (BP) algorithm to perform inference efficiently. Experimental results verify that the proposed algorithm significantly improves detection performance as the number of target items increases.