Having Your Cake and Eating It: An Analysis of Concession-Abuse-as-a-Service Zhibo Sun∗, Adam Oest∗, Penghui Zhang∗, Carlos Rubio-Medrano‡ Tiffany Bao∗, Ruoyu Wang∗, Ziming Zhao¶, Yan Shoshitaishvili∗, Adam Doupé∗, Gail-Joon Ahn ∗§ ∗Arizona State University, ‡Texas A&M University - Corpus Christi ¶Rochester Institute of Technology, §Samsung Research ∗{zhibo.sun, aoest, penghui.zhang, tbao, fishw, yans, doupe, gahn}@asu.edu ‡
[email protected], ¶
[email protected] Abstract companies in the difficult position of choosing between scam mitigation and the happiness of legitimate customers. Concession Abuse as a Service (CAaaS) is a growing scam A perception by vendors who fall victim to concession service in underground forums that defrauds online retailers abuse may be that these attacks are isolated incidents and through the systematic abuse of their return policies (via social can thus be resolved in an ad-hoc fashion. However, through engineering) and the exploitation of loopholes in company a comprehensive analysis of underground forums and a protocols. Timely detection of such scams is difficult as they concession abuse provider, we find that such attacks operate are fueled by an extensive suite of criminal services, such at scale, target merchants across multiple industry sectors, as credential theft, document forgery, and fake shipments. involve complex coordination between different underground Ultimately, the scam enables malicious actors to steal arbitrary actors, and overcome current industry best practices and goods from merchants with minimal investment. mitigations to reliably yield success for the criminals. In this paper, we perform in-depth manual and automated In this paper, we show that concession abuse is, in fact, analysis of public and private messages from four large a prevalent criminal business service to which even unso- underground forums to identify the malicious actors involved phisticated cybercriminals can subscribe and subsequently in CAaaS, carefully study the operation of the scam, and profit with minimal investment.