Operating System Security

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Questions and Answers

What is the primary goal of protection in a system?

To ensure optimal system performance

To provide maximum privileges to users and programs

To increase system complexity

To prevent malicious misuse of the system (correct)

What principle dictates that programs, users, and systems be given just enough privileges to perform their tasks?

Principle of equal privilege

Principle of maximum privilege

Principle of least privilege (correct)

Principle of absolute privilege

What is the recommended practice for a System Administrator's account?

Have a separate ordinary account for normal activities (correct)

Use a separate account for administrative tasks only

Share a single account with other administrators

Use the root account for normal day-to-day activities

What is the main principle that guides the access control mechanism in a system?

Need-to-know principle Signup and view all the answers

What is a computer viewed as in the context of protection?

A collection of processes and objects (both HW & SW) Signup and view all the answers

What is a protection domain in the context of access control?

A set of objects and their corresponding access rights Signup and view all the answers

What is the purpose of giving a program special privileges, such as making it a SGID program?

To limit the amount of damage that can occur if something goes wrong Signup and view all the answers

What is a potential issue with the use of SUID programs?

They can be placed in random directories around the system Signup and view all the answers

What is the main purpose of using special directories for privileged programs?

To prevent crackers from placing SUID programs in random directories Signup and view all the answers

What is an access right in the context of access control?

The ability to execute an operation on an object Signup and view all the answers

What is the purpose of giving each user their own account?

To limit users to modifying only their own files Signup and view all the answers

What is required to change the contents of a domain dynamically in a system with static domain association?

A mechanism for domain switching Signup and view all the answers

In the MULTICS system, what determines the access privileges of a process?

The current-ring-number associated with the process Signup and view all the answers

In UNIX, how are domains realized?

As users Signup and view all the answers

What is the consequence of a process operating in a particular ring in the MULTICS system?

It can access segments associated with higher rings Signup and view all the answers

What is the effect of setting the SUID bit on a program in UNIX?

Changes the user ID temporarily Signup and view all the answers

What is the primary principle underlying the MULTICS system's access control mechanism?

Need-to-know principle Signup and view all the answers

What is the benefit of using a ring structure in the MULTICS system?

It allows for finer-grained access control Signup and view all the answers

Study Notes

Goals of Protection

Prevent malicious misuse of the system by users or programs
Ensure shared resources are used according to system policies
Minimize damage caused by errant programs

Principles of Protection

Principle of least privilege: grant only necessary privileges to perform tasks
Limit potential damage by giving minimal privileges
Each user has their own account with limited privileges
Root account should not be used for normal activities

Domain of Protection

A computer system consists of processes and objects (HW & SW)
Objects can be abused if not protected
Alternative protection methods: placing privileged programs in special directories or using privileged daemons

MULTICS System

Uses a ring structure with 7 rings, each corresponding to a protection domain
Each ring has a subset of privileges of the inner rings
Files are memory segments with ring numbers and access privileges
Processes run in a ring and can only access segments in higher rings

Need to Know Principle

A process should only have access to necessary objects
Access should be limited to necessary modes and time frames
Modes available depend on object type

Domain Structure

A protection domain specifies accessible resources and operations
Defined as a set of pairs
Domains can be disjoint or overlapping
Association between process and domain can be static or dynamic

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Description

This quiz covers the concept of the need-to-know principle in operating system security, including protection domains and access control.