Security Evaluation of Multimedia Systems

High popularity of VoIP in last few years leads to higher concern of hackers. Many solutions of VoIP servers are created, but security was not always the top feature of these solutions. IP telephony infrastructure provides also other services, which are not related only to VoIP traffic. All these factors lead to a situation, when a VoIP server easily becomes a target of attacks. A wide spectrum of attacks can be done against VoIP, starting from misuse attacks, congestion of existing infrastructure to a completely (or partially) denial of service. Very popular are also SPIT attacks – an analogy to spam e-mail messages. Typical SPIT attacks are unwanted, automatically dialed prerecorded calls with commercial content. This paper deals with the need of application for automatic testing VoIP server robustness against different types of attacks. This application was developed on VSB-TUO Ostrava as a testing tool to verify if the target VoIP PBX is adequately secured and protected against any real threats. The system tests the SIP element for several usually occurring attacks and compiles evaluation of its overall security based on successful or unsuccessful penetrations. The article describes the application and algorithms that are used by system. Another way to improving VoIP server security is an automatic defense mechanism, which blocks incoming attacks – typically various Denial-of-Service (DoS) attacks. This proposed solution is based on Snort and SnortSam and has been implemented and evaluated in a test bed. Different DoS attack types are described in detail and knowledge is used to test the robustness of the VoIP server. These two applications give us an effective way for complex testing of VoIP infrastructure key elements and to effective blocking of unwanted, malicious traffic.



  • Miroslav Voznak
  • Filip Rezac

Part of session

Security and tools

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