access control

Question 1

authentication vs authorization vs audit

Answer 1

> authentication refers to the VERIFICATION of a valid user/system entity

> authorization refers to granting permissions for user/system entity to access resources

> audit refers to the process of examining and reviewing system records

Question 2

what are the four access control policies

Answer 2

1) DAC: discretionary access control
2) MAC: mandatory access control
3) RBAC: role-based access control
4) ABAC: attribute-based access control

Question 3

what is a subject and how many are there

Answer 3

an entity capable of accessing objects
- owner
- group
- world

Question 4

access control matrix for DAC

Answer 4

• rows are the users (user1,user2,….,usern)
• columns are the files (file1,file2,…,filen)
• {row,column} contains the permissions-> r,w,x

Question 5

access control list for DAC

Answer 5

• has user name at the top then a horizontal line beneath it
• beneath the horizontal lines are the access permissions->r,w,x then another horizontal line
• below the horizontal line draw an arrow that points to another list for another user

Question 6

capability list for DAC

Answer 6

• has file name at the top then a horizontal line beneath it
• beneath the horizontal lines are the access permissions->r,w,x then another horizontal line
• below the horizontal line draw an arrow that points to another list for another file

Question 7

steps triggered by an access attempt

Answer 7

• Sn attempts to issues a request for type a for object X
• the system generates a message to the controller for X as: {Sn,a,X}
• the controller checks the access control matrix for a in A{Sn, X}
• if true, then access is allowed
  else, a warning is issued

Question 8

what are inodes (index nodes)

Answer 8

• a data structure in a file system that stores metadata and pointers to the actual data of a file

Question 9

what is stored in indes

Answer 9

• file attributes
• permissions
• control information

Question 10

what are the fields of inodes and what do they mean

Answer 10

1) UID: username of owner
2) GID: group of owner
3) atime: access time
4) mtime: modification time (file content)
5) ctime: alteration time (file metadata)
6) block count: size of file

Question 11

what is DAC

Answer 11

the resource owner has the ability to exercise control over access permissions for their resources

Question 12

what is MAC

Answer 12

access permissions are determined and enforced by a central authority or security policy
- predefined rules

Question 13

what is RBAC

Answer 13

access permissions are assigned based on predefined roles

Question 14

access control matrix for RBAC

Answer 14

• rows are the users
• columns are the roles
• {row,column} = 1 or = 0 for every user