Collusive Review Spammer Detection Using Markov Random Fields

Product reviews are extremely valuable for online shoppers in providing purchase decisions.Driven by immense profit incentives,fraudsters deliberately fabricate untruthful reviews to distort the reputation of online products.As online reviews become more and more important,group spamming,i.e.,a team of fraudsters working collaboratively to attack a set of target products,becomes a new fashion of review spamming.Previous works use review network effects,i.e.the relationships among reviewers,reviews,and products,to detect fake reviews or review spammers,but ignore time effects,which is critical in characterizing group spamming.In this paper,we propose a novel Markov random field(MRF)-based method(ColluEagle)to detect collusive review spammers,as well as review spam campaigns,considering both network effects and time effects.First,we identify co-review pairs,a review phenomenon that happens between two reviewers who review a common product in a similar way,and then model reviewers and their co-review pairs as a pairwise-MRF and use loopy belief propagation to evaluate the suspiciousness of reviewers.We further design a high quality yet easy-to-compute node prior for ColluEagle,through which the review spammer groups are subsequently identified.Experiments show that ColluEagle can not only detect collusive spammers with high precision,significantly outperforming state-of-the-art baselines--FraudEagle and SpEagle,but also identify high quality review spammer campaigns.