Detecting Ringing-Based DoS Attacks on VoIP Proxy Servers

摘要

NGN (Next Generation Network) is often called all-IP network as the general idea behind NGN is that one network transports all information and services. When NGN is deployed in a large scale, VoIP will eventually replace PSTN, the traditional model of voice telephony. While VoIP promises both low cost and a variety of advanced services, it may entail security vulnerabilities. Unlike PSTN, intelligence is placed at the edge and the security measures are not incorporated into the network. VoIP-specific attacks have already been introduced, of which the ringing-based DoS attack belongs. In this paper, we propose a detection system of the ringing-based DoS attacks. We model the normal traffic of legitimate users with the gamma distribution and then quantify the discrepancy between the normal traffic and the attack traffic with Pearson's chi-square statistic. Simulation results show that the proposed detection system can reliably detect the ringing-based DoS attacks.