Probability Based Risk Analysis for a VoIP System

The increasing demand for voice over IP (VoIP) and the accompanying network convergence lead into a new area of security risks for voice infrastructures. A probability based risk analysis as an integral part of a security concept is presented which forges a hardened base system operating a voice platform. A modeling approach and a detailed system architecture is derived for the VoIP base system. Finally the security concept that was exemplarily implemented using freely available software packages (e.g. Linux, Asterisk) is described and results from verifications with several security test suites are highlighted.