Abusing SIP Authentication

Abstract

The recent and massive deployment of voice over IP infrastructures had raised the importance of the VoIP security and more precisely of the underlying signalisation protocol SIP. In this paper, we will present a new attack against the authentication mechanism of SIP. This attack allows to perform toll fraud and call hijacking. We will detail the formal specification method that allowed to detect this vulnerability, highlight a simple usage case and propose a mitigation technique.