Forensic Identification of Anonymous Sources in OneSwarm

OneSwarm is a p2p system for anonymous file sharing. We quantify the system’s vulnerability to three attacks that identify the sources of files. First, we detail and prove that a timing attack allows a single attacker to investigate all its neighbors for possession of specific files. We prove the attack is possible due to OneSwarm’s design and is unthwarted by changes made to OneSwarm since we released our attack. Second, we show that OneSwarm is much more vulnerable to a collusion attack than previously reported, and we quantify the attack’s success given a file’s popularity, a factor not evaluated earlier. Third, we present a novel application of a known TCP-based attack. It allows a single attacker to identify whether a neighbor is the source of data or a proxy for it. Each of these attacks can be repeated as attackers quit and rejoin the network. We present these attacks in the context of forensics and the investigation of child pornography. We show that our attacks meet the higher standards required of law enforcement for criminal investigations.