A Stealthy Attack Against Tor Guard Selection

Tor is a popular low-latency anonymous communication system which could provide anonymity and anti-censorship. Based on previous researches on de-anonymization of Tor, this paper proposes a novel approach to attack users’ guard selection which can pose great threat against Tor users' anonymity. Under the current design of Tor, once entry guards are compromised, the probability that an attacker observes both ends of a Tor circuit will be highly improved. Actual and simulated experiments both show that an attacker (e.g., a local or national government which have the power to monitor a Tor user’s internet connection) can successfully compromise a specific Tor user’s entry guard in about 30 minutes, and this can further help de-anonymize the user’s anonymous communication.