The Abuse Sharing Economy: Understanding the Limits of Threat Exchanges

The underground commoditization of compromised hosts suggests a tacit capability where miscreants leverage the same machine-subscribed by multiple criminal ventures-to simultaneously profit from spam, fake account registration, malicious hosting, and other forms of automated abuse. To expedite the detection of these commonly abusive hosts, there are now multiple industry-wide efforts that aggregate abuse reports into centralized threat exchanges. In this work, we investigate the potential benefit of global reputation tracking and the pitfalls therein. We develop our findings from a snapshot of 45 million IP addresses abusing six Google services including Gmail, YouTube, and ReCaptcha between April 7 April 21, 2015. We estimate the scale of end hosts controlled by attackers, expose underground biases that skew the abuse perspectives of individual web services, and examine the frequency that criminals re-use the same infrastructure to attack multiple, heterogeneous services. Our results indicate that an average Google service can block 14% of abusive traffic based on threats aggregated from seemingly unrelated services, though we demonstrate that outright blacklisting incurs an untenable volume of false positives.