Review on Attack and Defense in Tor

Abstract

Tor is currently the most famous tool of anonymous TCP communications for clients who need security, privacy and anonymity in their low-latency communications over the public network such as Internet. For this purpose, Tor provides reliable ways of communication through randomly selecting relay network circuits on client’s request to offer a secure communication path. However, several research papers are available which identify weaknesses of Tor that attackers can exploit to reveal a client’s identity. This paper highlights a few such Tor’s weaknesses through which attackers can launch snooping attacks on Tor. Some major attacks are discussed and it is observed that most attacks are launched at application-level protocols such as HTTP after compromising exit node or both entry and exit nodes of Tor relay circuits. Countermeasures against such attacks are also identified to increase security and anonymity over Tor based communications.