Remote sensing devices have emerged as a significant technology that enables the monitoring of processes and physical environment from far away locations. These remote sensing systems include physiological sensors installed on human body to continuously monitor the health and enable the fast detection of medical emergencies and the delivery of therapies (Body Area Networks-BAN), smart buildings that detect absence of occupants and shut down the cooling unit to save energy, data centers that use solar energy for cooling purposes, and unmanned aerial vehicles (UAVs) that use an image of the terrain to perform surveillance. They have been used to provide services such as automated pervasive health care, smart electricity grid, green cloud computing, and surveillance with UAVs. Since these systems utilize information from the physical environment and in turn affect the physical environment during their operation, any vulnerabilities, threats and attacks can expose the monitored process or physical environment to a number of risks. This paper seeks to develop Cyber Physical System Security Model for protecting remote sensing devices. The paper also investigated the tight coupling between the cyber and the physical in Cyber Physical Systems (CPSs), to establish the various forms of risks that have not been considered adequately in the traditional computing domain such as the cyber element adversely affecting the physical environment.