Advanced Flooding Attack on a SIP Server

Voice over IP is gaining more popularity in today´s communications. The Session Initiation Protocol (SIP) is the most popular VoIP signalling protocol is vulnerable to many kinds of attacks. Among all these attack, flood-based denial of service attacks have been identified as the biggest threat to SIP. Even though a great deal of research has been conducted into mitigating denial of service attacks, only a small proportion have been specific to SIP. This paper examines how denial of service attacks affect the performance of a SIP-based system, and proposes an Improved Security-Enhanced SIP System (ISESS) to mitigate such attacks. Experimental results are provided to demonstrate the effectiveness of ISESS. The experimental results show that with ISESS, during a flood-based denial of service attack, the performance of the system can be improved substantially.