Rating behavior evaluation and abnormality forensics analysis for injection attack detection

摘要

Collaborative recommender systems (CRSs) have become an essential component in a wide range of e-commerce systems. However, CRSs are also easy to suffer from malicious attacks due to the fundamental vulnerability of recommender systems. Facing with the limited representative of rating behavior and the unbalanced distribution of rating profiles, how to further improve detection performance and deal with unlabeled real-world data is a long-standing but unresolved issue. This paper develops a new detection approach to defend anomalous threats for recommender systems. First, eliminating the influence of disturbed rating profiles on abnormality detection is analyzed in order to reduce the unbalanced distribution as far as possible. Based on the remaining rating profiles, secondly, rating behaviors which belong to the same dense region using standard distance measures are further partitioned by exploiting a probability mass-based dissimilarity mechanism. To reduce the scope of determining suspicious items while keeping the advantage of target item analysis (TIA), thirdly, suspected items captured by TIA are empirically converted into an associated item-item graph according to frequent patterns of rating distributions. Finally, concerned attackers can be detected based on the determined suspicious items. Extensive experiments on synthetic data demonstrate the effectiveness of the proposed detection approach compared with benchmarks. In addition, discovering interesting findings such as suspected items or ratings on four different real-world datasets is also analyzed and discussed.