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CS6035 - Intro to Info Sec > P1L3: Operating Systems > Flashcards

P1L3: Operating Systems Flashcards

1
Q

What does an Operating System do? What does it provide?

A
  • -Makes it easier to use resources
  • -Hardware controlled by OS
  • -Provides isolation
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2
Q

What is a Trusted Computing Base (TCB)?

A

–OS has direct control of hardware resources

–OS must determine authorized user(s) of resources

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3
Q

What are TCB Requirements?

A
  1. Complete Mediation–OS is between HW resources and apps
  2. OS must be tamper-proof
  3. OS must be correct–Protected resources are used properly.
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4
Q

OS and Resource Protection

A

–Establish the source of the request (ie authentication)

–Authorization or Access Control

–OS follows policies for authorization and authentication

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5
Q

What are System calls?

A

A request to the operating system.

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6
Q

What is Complete Mediation?

A

Ensures that the OS cannot be bypassed when accessing a protected resource

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7
Q

What are the requirements for isolation?

A

–requires HW support for memory protection

–The processor must keep track of what kind of code is being executed

–Privileged instructions can only be executed in system mode

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8
Q

Are system calls more expensive than regular function calls? If so, why?

A

Yes. Because of the info that must be saved, the memory mapping that must be done, and the special instructions.

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9
Q

What is Memory Protection?

A

The HW determines if memory belongs to the OS and is therefore unwritable to users.

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10
Q

How do processes achieve unit isolation?

A

Each process gets an address space for it to use

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11
Q

What are Physical addresses?

A

Point to actual RAM or physical memory

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12
Q

What are Logical addresses?

A

Point to the address space

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13
Q

What is Address translation?

A

The translation between the logical and physical memory.

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14
Q

Logical addresses are stored on ____

A

pages

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15
Q

Physical addresses are stored on _____

A

frames

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16
Q

What is a Page table?

A

Table used to translate between pages and frames. It is built and protected by the OS

17
Q

Performing regular backups of data on a system is a critical control that assists with maintaining the integrity of the system and user data. T/F

A

True

18
Q

The default configuration for many operating systems usually maximizes security. T/F

A

False

19
Q

Each layer of code needs appropriate hardening measure in place to provide appropriate security services. T/F

A

True

20
Q

A malicious driver can potentially bypass many security controls to install malware. T/F

A

True

21
Q

It is possible for a system to be compromised during the installation process. T/F

A

True

22
Q

_____ applications is a control that limits the programs that can execute on the system to just those in the explicit list.

A

White-listing

23
Q

The most important changes needed to improve system security are to _____.

A
  1. disable remotely accessible services that are not required
  2. ensure that applications and services that are needed are appropriately configured
  3. disable services and applications that are not required
24
Q

Security concerns that result from the use of virtualized systems include:

A
  1. Guest OS violation.
  2. Guest OS monitoring by the hypervisor.
  3. Virtualized environment security.
25
Q

Once the system is appropriately built, secured and deployed, the process of maintaining security is _____.

A

Continuous

26
Q

The first critical step in securing a system is to secure the _____.

A

Base Operating System

27
Q

The first step in deploying new systems is _____.

Planning

A

Planning

28
Q

Which of the following need to be taken into consideration during the system security planning process

A
  1. how users are authenticated
  2. the categories of users of the system
  3. what access the system has to information stored on other hosts
29
Q

Guest OSes are managed by a ________ , or VMM, that coordinates access between each of the guests and the actual physical hardware resources.

A

Hypervisor, virtual machine monitor

30
Q

_______-is a reactive control that can only inform you about bad things that have already happened.

A

Logging

31
Q

The three operating system security layers are: physical hardware, operating system kernel and _________

A

User Applications and Utilities

32
Q

__________ refers to a technology that provides an abstraction of the computing resources that run in a simulated environment.

A

Virtualization

33
Q

The final step in the process of initially securing the base operating system is_________

A

security testing

34
Q

What does Hardening mean?

A

to make more secure

35
Q

What are the Requirements of a TCB (trusted computing base)

A

Isolation (tamper proof), Complete mediation, verifiable (correct)

36
Q

Call Gates

A

System calls used to transfer control between user and system

37
Q

Memory Management Unit (MMU)

A

Uses page tables to resolve virtual addresses to physical addresses

38
Q

User code cannot access physical resources. T/F

A

True, only system mode’s privileged instructions can

39
Q

What are Virtualization’s 4 security layers?

A

Physical hardware, Hypervisor/VMM, Guest Os Kernel, User Apps

CS6035 - Intro to Info Sec (23 decks)

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