Improving IoT System Resilience through Secure MQTTv5 Shared Subscriptions

In the rapidly evolving landscape of the IoT, the deployment of Wireless Sensor Networks (WSNs) plays a crucial role in enabling smart environments. Future WSN IoT deploy-ments are characterized by a massive number of interconnected devices, necessitating robust communication protocols to handle the vast amount of data generated and transmitted in the so-called Massive IoT (M-IoT) context. Focusing on the con-strained nature of sensors, the MQTT protocol introduces, with the MQTTv5 specification, a pivotal technology for enhancing resource utilization and connectivity efficiency in WSN IoT scenarios: the shared subscription mechanism. In the context of M-IoT WSNs, security vulnerabilities are further exacerbated, potentially leading to high-scale damage. Based on these consider-ations, the objective of this work is to provide a security-oriented examination of the shared subscription feature proving how malicious users can exploit it to induce an indefinite starvation status among the legacy subscribers of the IoT deployment. We highlighted the extent of the damage of the shared subscription attack proposing a countermeasure that takes into account both the light nature of MQTT and the impact that it could have in future M-IoT deployment testing it under real IoT traffic patterns.