We discover two vulnerabilities of the VoWi-Fi service, and develop a detection system against them. First, the adversary can hijack its signaling session and exploit it to launch DoS attacks or generate ghost calls. Second, the adversary can hijack its voice call session, and hide data in voice messages to usurp network resource. We have confirmed both vulnerabilities in operational cellular networks.

We are the first group that discovers security vulnerabilities of the IMS system by hijacking  VoWi-Fi sessions, and develops their detection system. We uncover two critical vulnerabilities from the highly protected IMS system. They can be exploited to launch DoS attacks, generate ghost calls, and usurp network resource. We have validated that they are common security issues worldwide.

Our achievement focuses on common security threats in 4G/5G networks worldwide. It can benefit carriers and network/phone vendors. The security threats are rooted in the flaws of their products that support VoWi-Fi service and IMS system. Our detection system can help carriers and vendors detect those vulnerabilities, and our experience can assist them in fixing the security issues without suffering huge monetary loss.