Operating System Security:

1. Security refers to providing a protection system to computer system resources such as CPU, memory, disk, software programs and most importantly data/information stored in the computer system.

2. If a computer program is run by an unauthorized user, then he/she may cause severe damage to computer or data stored in it.

3. So a computer system must be protected against unauthorized access, malicious access to system memory, viruses, worms etc.

Authentication:

Authentication refers to identifying each user of the system and associating the executing programs with those users. It is the responsibility of the Operating System to create a protection system which ensures that a user who is running a particular program is authentic.

One Time passwords:

One-time passwords provide additional security along with normal authentication. In One-Time Password system, a unique password is required every time user tries to login into the system.

Program Threats:

Operating system's processes and kernel do the designated task as instructed. If a user program made these process do malicious tasks, then it is known as Program Threats.

System Threats:

System threats refers to misuse of system services and network connections to put user in trouble. System threats can be used to launch program threats on a complete network called as program attack. System threats creates such an environment that operating system resources/ user files are misused.