Effectiveness and detection of denial of service attacks in Tor

TL;DR

This paper evaluates a denial of service attack on Tor using analytical and simulation methods, and proposes two algorithms for detecting such attacks, enhancing understanding of Tor's vulnerabilities.

Contribution

It introduces two novel algorithms for detecting DoS attacks on Tor, one deterministic and one probabilistic, with validation through analysis and simulation.

Findings

The attack significantly increases the risk of compromising Tor's anonymity.

The deterministic detection algorithm is proven correct.

The probabilistic detection algorithm is verified through simulation.

Abstract

Tor is currently one of the more popular systems for anonymizing near real-time communications on the Internet. Recently, Borisov et al. proposed a denial of service based attack on Tor (and related systems) that significantly increases the probability of compromising the anonymity provided. In this paper, we analyze the effectiveness of the attack using both an analytic model and simulation. We also describe two algorithms for detecting such attacks, one deterministic and proved correct, the other probabilistic and verified in simulation.