The Fault in the Stars: Understanding Underground Incentivized Review Services

Product reviews play an important role in rankings and impact customers' purchasing decisions on e-commerce sites. There exists a thriving ecosystem of incentivized reviews on e-commerce marketplaces -- reviews written by real customers in exchange for free products. While some e-commerce marketplaces themselves support incentivized review programs to solicit honest high-quality reviews, there are parallel underground services that sellers can use to commission fake positive reviews from real customers in exchange for free products. Despite anecdotal reports, our understanding of how these incentivized services operate and, crucially, how are they able to resist takedown efforts is lacking. In this paper, we conduct a quantitative and qualitative study of incentivized review services by infiltrating an underground incentivized review service geared towards Amazon.com. On a dataset of 1600 products seeking incentivized reviews, we first demonstrate the ineffectiveness of off-the-shelf fake review detection as well as Amazon's existing countermeasures. Through a survey of more than 70 participants of this underground incentivized review service, we uncover fairly sophisticated recruitment, execution, and reporting mechanisms they use to scale their operation while resisting takedown attempts.