[Solved] CSCI262 System Security Assignment 2

Make sure you include referencing for answers where it would obviously be needed.

1. You have two puzzles with parameters as follows:

Puzzle A: One subpuzzles. k = 6.

Puzzle B: Eight sub-puzzles. k = 3.

You should provide, for both cases other than part (b), the following:

• The distribution of the number of cases that require each number of hashes. 1 Mark
• Explain the method you used to obtain your distributions. Dont go into too many detailsor show working, its more I wrote a C++ program to and then using I . 5 Mark
• A graph of the distribution of the data above. 5 Mark
• The average number of hashes needed. 5 Mark
• The standard deviation for the distribution of the number of hashes needed. 5 Mark

You should assume that if there are N possible solutions you check the N^th by hashing even if all others have failed and there has to be a solution.

2. Which general security principle is violated in the following pseudo-code? Modify the pseudo-codeto fix the potential security problem. 1 Mark

permit = CheckAccess() IF (permit == Access_Denied) Print Access Denied

ELSE

Print Access Granted

Run Function()

3. Consider that the incidence of viral attachments in email messages in 1 in 800. Your malware checkerwill correctly identify a message as viral 95% of the time. Your malware checker will correctly identify a message as nonviral 95% of the time. Your malware checker has just flagged a message as being malware. What is the probability that the message is actually okay? Justify your answer using Bayes theorem. 1 Mark
4. Describe, in your own words, a specific instance of an insider placing malware within a system. Youshould describe the type of malware placed, the expected likely impact, and some details regarding the outcome. This is not meaning a hypothetical scenario you have made up, find an actual real world example. 2 Marks
5. Every hour the worm X spreads from each infected computer to one previously uninfected computers. In answering these questions you should explain how you determined your answers.
   • Give a table showing the number of infected computers at each hour across a 24 hour period.

At time t = 0 the number of X infected computers is N = 1. 0.5 Mark

• By time t = 6.5 a counter worm W has been developed and it is deployed on one infected computer. W removes malware X from any host W is on. The counter worm W spreads slightly more quickly than X, with each W spreading to two X infected hosts each hour, provided such hosts are available.

Provide another table showing the spread of W and the impact on X across an appropriate time frame, starting from t = 0 again.

Note the offset in time means that at t = 6.5 the number of X infected computers reduces by 1, so the spread of t = 7 will be slightly smaller than before. Overall the number of X infected computers will go up on the hour, and down on the half hour. 1.5 Marks

• Graph the two cases against each other, clearly indicating on it where N = 0. 5 Mark
• Assume that at time t = 9, X evolves to spread to three uninfected computers each hour. What subsequently happens? 5 Mark

6. Briefly describe, in your own words, each of the following. Be sure to specify the domain and natureof each.