Vulnerabilities of the Real-Time Transport (RTP) Protocol for Voice over IP (VoIP) Traffic

Over the past decade, Voice over IP (VoIP) has revolutionalized the telecommunications industry. VoIP has become more prevalent than ever, and consequently more users have switched to IP-based data networks for their telephone use from the analogue Public Switched Telephone Network (PSTN). One challenge, though, is to secure and protect these VoIP connections. In this paper, we investigate a new approach to demonstrate the vulnerability of VoIP connections. Our approach monitors real-time data streams (e.g., RTP), and inserts packets containing fraudulent voice data at expected times estimated from the monitoring. As false packets are well-aligned with original packets, we can maximize the effects of the test while minimizing the number of inserted packets. This minimal number of false packets also helps eschew the detection efforts of denial-of- service defense mechanisms. Our results indicate that the inserted packets at desired times can indeed disrupt the original RTP stream without any noticeable traffic increase.