Cs 465 Homework 3 Fall 2009

CS 465 Introduction to Computer Security Homework Assignment #3 Assigned: Thursday, November 19, 2009 Due: Tuesday, December 1, 2009 at the beginning of the class, hard copy No assignments will be accepted after 9:30 am on Tuesday, December 8, 2009

Name Student ID 1 /15

2 /15

3 /10

4 /15

5 /10

6 /35

7 /10 Extra credit

Total /100

1. Alice can read and write to file A, can read the file B, and can execute the file C. Bob can read A, can read and write to B, and cannot access C.

a. Write a set of Access Control Lists (ACL) for this situation. With what is each list associated? b. Write a set of capability lists for this situation. With what is each list associated? c. Explain why Access Control Lists are used much more often for access control in operating systems than Capabilities. (15 points)

2. Debra, Raymond, Marie, and Frank belong to the same group of users. Debra is an owner of the file Kids and she wants to allow the whole group except Marie to read the file Kids and only Raymond to write into the file Kids. Explain how and under what conditions Debra can accomplish this in a. Standard UNIX b. Windows XP. (15 points) 3. How does the "Secure Desktop" feature in Windows Vista help with security? (10 points) 4. Consider a system which combines the Military security policy and Bell-La Padula

confidentiality model. Given the security levels TOP SECRET, SECRET, CONFIDENTIAL, and UNCLASSIFIED (ordered from highest to lowest), and compartments Students, Faculty, and Staff, specify what type of access (read, write, both, none) is allowed in each of the following situations. (15 points) a. Paul, cleared for (TOP SECRET, {Faculty, Staff, Students}), wants to access a document classified as (TOP SECRET, {Faculty, Staff}). b. Anna, cleared for (CONFIDENTIAL, {Faculty, Students}), wants to access a document classified as (CONFIDENTIAL, {Staff})

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c. Jesse, cleared for (SECRET, {Faculty, Students}), wants to access document classified as (CONFIDENTIAL, {Students}). d. Sam, cleared for (CONFIDENTIAL, {Faculty, Staff}), wants to access a document classified as (SECRET, {Staff}). e. Robin cleared for (CONFIDENTIAL, {Staff}) wants to access a document classified as (UNCLASSIFIED, {Staff}). 5. The conflict class “Airlines” contains the following company groups: Delta, United Airlines, American Airlines, and US Airways. The second conflict class “Hotels” contains the company groups: Holiday Inn, Inter Continental, Best Western, and Double Tree. For each of the following scenarios determine whether the user would be allowed access under the Chinese Wall security policy. Justify your answers. d. Tom has had access to Delta company group. Tom wants to get access to United Airlines company group. e. Bob has had access to Delta company group. Bob wants to get access to Holiday Inn company group. f. Jim wants to get access to Delta and United Airlines company groups. g. John wants to get access to Delta and Inter Continental company groups. h. Ann wants to get access to Double Tree company group. (10 points)

6. One problem with database security is inference with the outside knowledge pertaining to the records in the database. Consider the following scenario. Jack was outside, watering his lawn, when he saw an ambulance pull up to his neighbor’s house. Jack, being the nosy person that he is, decides to query the local hospital database (freely available for statistical analysis) and see what he can find out. The results of his query are given in Table 1.

Gender M

Date of Birth */*/1976

M F M F F F M F

*/*/1952 */*/1966 */*/1975 */*/1973 */*/1962 */*/1951 */*/1949 */*/1976

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Table 1 Zip Code 26554

26554 26554 26505 26554 26505 26505 26554 26505

Illness Reflex Sympathetic Dystrophy Cancer Cystic Fibrosis Skin Lesions Cancer Osteoporosis Arthritis Heart Disease Ingrown Toenail

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Jack also has the following outside knowledge. • His neighbor is a male who lives in Fairmont WV (because he lives beside him). • Jack's neighbor mentioned watching the last episode of “I Love Lucy” (the actual broadcast, not rerun). • Jack's neighbor is Asian. Jack knows from watching the Discovery Channel that Asians have a reduced risk of heart disease.

Based on the results of the query and the outside knowledge, what is the most likely illness of Jack's neighbor? Explain your reasoning. (10 points) Another important risk to database security is the fact that combinations of non-sensitive data, gathered from the same or multiple databases, can be used to infer even more sensitive information. Consider the continuation of the previous scenario. Jack also decides to run some queries on the local voter registration database. The results of his queries are given in Tables 2 and 3.

Zip Code

Table 2 Age Bracket Gender

26505 26505 26505 26505 26505 26505

18-35 35-55 55+ 18-35 35-55 55+

F F F M M M

Address

William Smith

123 Willey St. Morgantown, WV 456 Grant Ave. Morgantown, WV 111 Overhill St. Fairmont, WV 222 Grove St. Morgantown, WV 333 Dudly St. Morgantown, WV

Kelsey Riddle Amanda Jones Sarah Ball

Average Income of Voters

2 4 1 1 3 7

25,000 41,000 30,000 45,000 55,000 30,000

Table 3 Political Affiliation

Name

John Robinson

Number of Registered Voters

Date of Birth

Republican

3/14/1967

Democrat

5/5/1975

Republican

7/13/1966

Democrat

9/6/1981

Independent

4/18/1951

Cross-reference the three query results given in Tables 1, 2, and 3 and infer as much information as possible about the 5 people listed in Table 3 (e.g., income, political affiliation, age, illness, etc). (15 points)

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What control(s) should be used to prevent revealing the sensitive data from Tables 1,2 and 3. Provide specific answers and give new tables. (10 points)

7. Describe how Auditing and Analyzing Access Control works in Windows XP. List and

describe at least five categories of events that can be audited in Windows XP. (10 points extra credit)

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