Answer:
Question Completed:
Use the following facts to assess the time-based model of security for the ABC Company; how well does the existing system protect ABC? Assume that the best-, average-, and worst-case estimates are independent for each component of the model.
1) Estimated time that existing controls will protect the system from attack = 15 minutes (worst case), 20 minutes (average case), and 25 minutes (best case)
2) Estimated time to detect that an attack is happening = 5 minutes (best case), 8 minutes (average case) and 10 minutes (worst case)
3) Estimated time to respond (or correct) to an attack once it has been detected = 6 minutes (best case), 14 minutes (average case), and 20 minutes (worst case)
Current Estimate
Case P D R Time based security(P>D+R)
Best 25 5 6 25 > 11
Average 20 8 14 20 < 22
Worst 15 10 20 15 < 30
Assumptions
A) Case P D R Time based security(P>D+R)
Best 30 5 6 30 > 11
Average 23 8 14 23 > 22
Worst 19 10 20 19 < 30
B) Case P D R Time based security(P>D+R)
Best 25 2 6 25 > 8
Average 20 4 14 20 > 18
Worst 15 7 20 15 < 27
C) Case P D R Time based security(P>D+R)
Best 25 5 3 25 > 8
Average 20 8 6 20 > 14
Worst 15 10 10 15 < 20
D) Case P D R Time based security(P>D+R)
Best 28 5 6 28 > 11
Average 22 8 14 22 = 22
Worst 17 10 20 17 < 30
E) Case P D R Time based security(P>D+R)
Best 25 4 6 25 > 10
Average 20 7 14 20 < 21
Worst 15 9 20 15 < 29
F) Case P D R Time based security(P>D+R)
Best 25 5 4 25 > 9
Average 20 8 9 20 > 17
Worst 15 10 12 15 < 22
Explanation:
Question 1) Which single investment would you recommend?
A single investment of $75,000 in option C. This gives a margin of +17 on the best case scenario and +6 on the average case scenario and -5 on the worst case scenario, which is the best alternative on the 3 scenarios as the joint outcome is +18 (17 + 6 - 5).
Question 2) Which combination?
Note that since the total amount is $100,000, the combination would be a $75,000 and a $25,000 investment
The combination of A and F, gives the best outcome on the 3 cases in comparison to other combinations
Case P D R Time based security(P>D+R)
Best 30 5 4 30 > 9
Average 23 8 9 23 > 17
Worst 19 10 12 19 < 22