A Comprehensive Survey on Attacks, Security Issues and Blockchain Solutions for IoT and IIoT

In recent years, the growing popularity of Internet of Things (IoT) is providing a promising opportunity not only for the development of various home automation systems but also for different industrial applications. By leveraging these benefits, automation is brought about in the industries giving rise to the Industrial Internet of Things (IIoT). IoT is prone to several cyberattacks and needs challenging approaches to achieve the desired security. Moreover, with the emergence of IIoT, the security vulnerabilities posed by it are even more devastating. Therefore, in order to provide a guideline to researchers, this survey primarily attempts to classify the attacks based on the objects of vulnerability. Subsequently, each of the individual attacks is mapped to one or more layers of the generalized IoT/IIoT architecture followed by a discussion on the countermeasures proposed in literature. Some relevant real-life attacks for each of these categories are also discussed. We further discuss the countermeasures proposed for the most relevant security threats in IIoT. A case study on two of the most important industrial IoT applications is also highlighted. Next, we explore the challenges brought by the centralized IoT/IIoT architecture and how blockchain can effectively be used towards addressing such challenges. In this context, we also discuss in detail one IoT specific Blockchain design known as Tangle, its merits and demerits. We further highlight the most relevant Blockchain-based solutions provided in recent times to counter the challenges posed by the traditional cloud-centered applications. The blockchain-related solutions provided in the context of two of the most relevant applications for each of IoT and IIoT is also discussed. Subsequently, we design a taxonomy of the security research areas in IoT/IIoT along with their corresponding solutions. Finally, several open research directions relevant to the focus of this survey are identified.