Robots have improved human life and increased the efficiency of performance in tasks that require precision and effort. For example, surgical robots are now used to perform precise surgical procedures and give accurate results. Moreover, robots are also used in elderly care to ease their lives. Perhaps there can even be self-driving cars that could deliver a person to their destination without the need of a driver. So it is very important to mention that these robots should be secure in terms of security for human life. Hence, this paper aims to explore the published studies on robots and their various security vulnerabilities. We review the most prominent weaknesses in the robotic operating system (ROS) and discuss some types of attacks against these robots. Also, this paper discusses the security enhancements to protect ROS that researchers have suggested protecting against some of the attacks and vulnerabilities that may occur on these robots. The primary findings of this work are to generate system copies for backup as well as encryption to protect against information disclosure. Also, a dynamic model is needed to detect and mitigate attacks that may occur in a physical manner, such as injecting malware into robots.