BitTorrent Needs Psychiatric Guarantees: Quantifying How Vulnerable BitTorrent Swarms are to Sybil Attacks

BitTorrent, one of the most popular content distribution protocols nowadays, has an identification generation scheme that is completely autonomous. Furthermore, BitTorrent uses a random mechanism to discover new peers. This leaves the system vulnerable to a sybil attack, by which an entity associates multiple identifications to itself in an attempt to fool the other peers that execute the agreed protocol and increase its utility. In this work we evaluate the impact of such an attack in a set of representative torrents derived from a large-scale measurement. Our analysis observed the dynamic of the interactions among the peers aiming at studying the behaviour of attacks in typical swarms of a community that shares files for free distribution. Our results show that, in general, the attack is effective and can be performed with few identities, what implies in low resource requirements for attackers.