Cell Counting Attack and Browser Attack against TOR Network

The onion router (TOR) allows to hide your identity various software under this categories are available that allows online anonymity network, supporting TCP applications over the Internet. It doesn't allow network surveillance or traffic analysis to get tracked but most of these software used equal size of cells (512B). In this paper we are comparing cell-counting attacks and browser attacks against TOR. Different from cell-counting attacks, these attacks can confirm anonymous communication relationships quickly and accurately by manipulating one single cell and pose a serious threat against Tor. A malicious entry onion router may duplicate, modify, insert, or delete cells of a TCP stream from a sender. The manipulated cells traverse middle onion routers and arrive at an exit onion router along a circuit. Because Tor uses the counter mode AES (AES-CTR) for encrypting cells, the manipulated cells disrupt the normal counter at exit onion routers and decryption at the exit onion router incurs cell recognition errors, which are unique to the investigated cell counting attacks. In Browser Attack, a user’s web browser into sending a distinctive signal over the Tor network that can be detected using traffic analysis. It is delivered by a malicious exit node using a man-in-the-middle attack on HTTP. Both the attack and the traffic analysis can be performed by an adversary with limited resources. While the attack can only succeed if the attacker controls one of the victim’s entry guards, the method reduces the time required for a traffic analysis attack on Tor from O(nk) to O(n + k), where n is the number of exit nodes and k is the number of entry guards