The connection of physical devices, buildings, home appliances, vehicles, and other things embedded with electronics, sensors, software, and actuators that facilitate these objects in networking is called the Internet of Things (IoT). IoT has drastically changed our lives by way of automating jobs across almost all industries. The application and adoption of it in industrial machine utilization, industrial processes, and manufacturing is known as the Industrial Internet of Things (IIoT). This IIoT is coined Industry 4.0, and is a subclass of IoT that focuses on industrial applications such as machine control and maintenance, optimizing industrial robotic systems in manufacturing, and industrial central monitoring systems. Integrating the operations of manufacturing companies in Industry 4.0 means exposing the company’s IT infrastructure and data, which makes it more susceptible and vulnerable to cyber threats. Shielding IIoT against cyber threats is crucial in order to control and stimulate the economic engine of the future. Protecting cyber systems from thievery and adversaries is essential since it includes everything that is appropriate for securing sensitive data, personal information, cerebral property, industry, and governmental information systems. Cyber security refers to the umbrella of processes, technologies, and tools intended to protect networks, programs, devices, and data from various cyber attacks, damage, and unauthorized access. Cyber security ought to be an essential part of design, strategy, and operations, and needs to be focused on from the start for any new connected, Industry 4.0-driven approach. This chapter focuses on providing a clear understanding of cyber space, cyber systems, and the security challenges inherent to Industry 4.0.