With regard to the control of computer-based information systems, answer the following:

(a) Describe some of the common security threats facing organisational computer-based information systems.

(b) Explain the four basic approaches to controlling computer-based information systems.
Highlight the advantages and disadvantages of each approach.

(c) ‘More effective protection for a computer-based information system can be achieved by employing a combination of the four basic approaches to control.’ Using relevant examples, discuss this statement.