This course introduces the fundamentals of operating systems (OS) security. The coverage includes access control mechanisms, memory protections, and OS-level mechanisms (hardware and software) and policies to protect against attacks and threats such as rootkits and malware. The course also includes the concepts of virtual machines and their use to understand and analyze modern OSs (including mobile OSs) in order to identify OS-related risks, threats, and vulnerabilities. Furthermore, this course consists of a set of laboratory experiments that provides hands-on experience in this topic.