星期一, 4月 25, 2011

Review Assessment: Test 8 Topic 9

COMPUTER CONTROL AUDITING AND SECURITY


Question 1
Which of the following has a security classification? (10.1)


A. a subject

B. an object

C. All of the above

D. None of the above


Correct answer is B.

In most security models, each subject and each object is assigned a security class. In the simplest formulation, security classes form a strict hierarchy and are referred to as security levels. A subject is said to have a security clearance of a given level; an object is said to have a security classification of a given level.


Question 2
What are the three rules specified by the BLP model? (10.2)


A. no read down, no write up and no property

B. ds-property, no read up and no write down

C. *-propety, no write up and security authorisation to a higher level object

D. none of the above


Correct answer is B.

no read up: A subject can only read an object of less or equal security level. This is referred to in the literature as the simple security property (ss-property).
no write down: A subject can only write into an object of greater or equal security level. This is referred to in the literature as the *-property.
ds-property: An individual (or role) may grant to another individual (or role) access to a document based on the owner's discretion, constrained by the MAC rules. Thus, a subject can exercise only accesses for which it has the necessary authorization and which satisfy the MAC rules.


Question 3
What does the Biba model deal with? (10.4)


A. unauthorised disclosure of information

B. integrity

C. confidentiality

D. unauthorised modification of information

E. Both B and D

F. Both A and C

G. None of the above


Correct answer is E.

The BLP model deals with confidentiality and is concerned with unauthorized disclosure of information. The Biba model deals with integrity and is concerned with the unauthorized modification of data.


Question 4
1 points Save
Which of the following are degrees of granularity that are possible with am MLS database? (10.11)


A. Entire database

B. Individual columns

C. Individual elements

D. Individual tables

E. Only B, C and D above

F. All of the above


Correct answer is F.
Refering to page 327 of the text, Stallings & Brown (2008), note the following:

Entire database: This simple approach is easily accomplished on an MLS platform. An entire database, such as a financial or personnel database, could be classified as confidential or restricted and maintained on a server with other files.

Individual tables (relations): For some applications, it is appropriate to assign classification at the table level. In the example of Figure 10.10a, two levels of classification are defined: unrestricted (U) and restricted (R). The Employee table contains sensitive salary information and is classified restricted, while the Department table is unrestricted. This level of granularity is relatively easy to implement and enforce.

Individual columns (attributes): A security administrator may choose to determine classification on the basis of attributes, so that selected columns are classified. In the example of Figure 10.10b, the administrator determines that salary information and the identity of department managers is restricted information.

Individual rows (tuples): In other circumstances, it may make sense to assign classification levels on the basis of individual rows that match certain properties. In the example of Figure 10.10c, all rows in the Department table that contain information relating to the Accounts Department (Dept. ID = 4), and all rows in the Employee Table for which the Salary is greater than 50K are restricted.

Individual elements: The most difficult scheme to implement and manage is one in which individual elements may be selectively classified. In the example of Figure 10.10d, salary information and the identity of the manager of the Accounts Department are restricted.



Question 5
What are the three basic services of the TPM? (10.13)


A. Microsoft firewall, anti virus software and encryption service

B. anti virus software, Microsoft Windows Malicious Software Removal Tool and SSL certification

C. authenticated boot service, certification service and encryption service

D. none of the above

Correct answer is C.

Authenticated boot service: The authenticated boot service is responsible for booting the entire operating system in stages and assuring that each portion of the OS, as it is loaded, is a version that is approved for use.

Certification service: Once a configuration is achieved and logged by the TPM, the TPM can certify the configuration to other parties. The TPM can produce a digital certificate by signing a formatted description of the configuration information using the TPM's private key. Thus, another user, either a local user or a remote system, can have confidence that an unaltered configuration is in use.

Encryption service: The encryption service enables the encryption of data in such a way that the data can be decrypted only by a certain machine and only if that machine is in a certain configuration.

Further details are provided on page 330 of the text, Stallings & Brown (2008).

Question 6
Under the Common Criteria Evaluation Assurance Levels, what is the highest level of assessment a product can be rated? (10.17)


A. EAL7

B. E1

C. EAL1

D. A1



Correct answer is A.
The highest Evaluation Assurance Level is EAL7.
Refer to your text, page 342 and 243, Computer Security Principles and Practice, Stalling & Brown, 2008.

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