On the Security Threat of Abandoned and Zombie Cellular IoT Devices

Abstract

The number of network-connected devices increased exponentially at least during the last two decades. Although the robustness and long-term stability of these devices are relatively high, many of them outlast the purpose of their installation, sometimes even the life-cycle of its serving connection technology.The number of long-living, radio-transmitting, abandoned devices keeps increasing, especially with new deployments of Internet of Things (IoT) endpoints. Such equipment occupy radio resources in both licensed and public radio bands; moreover, they seize processing resources in networking equipment. This worrying situation should be taken care of. In the short term we can identify and ban such devices, but in the long term, proper, standardized life-cycle management should be put in place.This paper demonstrates the manifestation of this problem on 3GPP-based cellular networks (3G, 4G, and 5G), although similar issues are threatening for WiFi, Bluetooth, ZigBee and LoRaWAN technologies, as well. Furthermore, the paper presents methods to identify abandoned, non-operated or zombie devices, and proposes methods on refusing their access to the network, or – in the cellular case – forcing them into radio silence.