The role of phone numbers in understanding cyber-crime schemes

Internet and telephones are part of everyone´s modern life. Unfortunately, several criminal activities also rely on these technologies to reach their victims. While the use and importance of the Internet has been largely studied, previous work overlooked the role that phone numbers can play in understanding online threats. In this work we aim at determining if leveraging phone numbers analysis can improve our understanding of the underground markets, illegal computer activities, or cyber-crime in general. This knowledge could then be adopted by several defensive mechanisms, including blacklists or advanced spam heuristics. Our results show that, in scam activities, phone numbers remain often more stable over time than email addresses. Using a combination of graph analysis and geographical Home Location Register (HLR) lookups, we identify recurrent cyber-criminal business models and link together scam communities that spread over different countries.