Botnets in 4G cellular networks: Platforms to launch DDoS attacks against the air interface

Botnets are overlay networks built by cyber-criminals from hacked smartphones and computers. In this paper, we report a vulnerability of the air interface of 4G cellular networks, the Long Term Evolution (LTE), to Distributed Denial-of-Service (DDoS) attacks launched from botnets. The attack scenario constitutes of a bot-master instructing the botnet nodes to start sending or downloading dummy data in order to overwhelm the air interface, thereby denying service for voice users. Through simulation using a capable LTE simulator, we determine the number of botnet nodes needed per cell that can effectively render the cellular network unusable. Specifically, we show that a botnet that has spread to only 3% of subscribers is capable of lowering the voice quality from 4.3 to 2.8 in Mean Opinion Score (MOS) scale of 1 to 5 for scheduling strategies designed for realtime flows. On the other hand, a botnet that has managed to spread to 6% of subscribers can cause a MOS value of 1, i.e., a complete outage. The threat identified and the reported results could inspire the implementation of new mechanisms to ensure the security and availability of vital telecommunication services.