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What is a secure database technique that could explain …

For competitive reasons, the customers of a large shipping company called the “Integrated International Secure
Shipping Containers Corporation” (IISSCC) like to keep private the various cargos that they ship. IISSCC uses
a secure database system based on the Bell-LaPadula access control model to keep this information private.
Different information in this database is classified at different levels. For example, the time and date a ship
departs is labeled Unclassified, so customers can estimate when their cargos will arrive, but the contents of all
shipping containers on the ship are labeled Top Secret to keep different shippers from viewing each other’s
cargos.
An unscrupulous fruit shipper, the “Association of Private Fruit Exporters, Limited” (APFEL) wants to learn
whether or not a competitor, the “Fruit Is Good Corporation” (FIGCO), is shipping pineapples on the ship “S.S.
Cruise Pacific” (S.S. CP). APFEL can’t simply read the top secret contents in the IISSCC database because of
the access model. A smart APFEL worker, however, attempts to insert a false, unclassified record in the
database that says that FIGCO is shipping pineapples on the S.S. CP, reasoning that if there is already a
FIGCO-pineapple-SSCP record then the insertion attempt will fail. But the attempt does not fail, so APFEL can’t
be sure whether or not FIGCO is shipping pineapples on the S.S. CP.
What is the name of the access control model property that prevented APFEL from reading FIGCO’s cargo
information? What is a secure database technique that could explain why, when the insertion attemptsucceeded, APFEL was still unsure whether or not FIGCO was shipping pineapples?

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A.
*-Property and Polymorphism

B.
Strong *-Property and Polyinstantiation

C.
Simple Security Property and Polymorphism

D.
Simple Security Property and Polyinstantiation

Explanation:
The simple security rule states that a subject at a given security level cannot read data that reside at a higher
security level. Simple Security Property is the name of the access control model property that prevented APFEL
from reading FIGCO’s cargo information.
The secure database technique that could explain why, when the insertion attempt succeeded, APFEL was still
unsure whether or not FIGCO was shipping pineapples is Polyinstantiation. Polyinstantiation enabled the false
record to be created.
Polyinstantiation enables a table that contains multiple tuples with the same primary keys, with each instance
distinguished by a security level. When this information is inserted into a database, lower-level subjects must be
restricted from it. Instead of just restricting access, another set of data is created to fool the lower-level subjects
into thinking the information actually means something else.
Incorrect Answers:
A: The *-property rule (star property rule) states that a subject in a given security level cannot write information
to a lower security level. This is not the access control model property that prevented APFEL from reading
FIGCO’s cargo information.
Polymorphism takes place when different objects respond to the same command, input, or message in different
ways. This is not the secure database technique used in this question.
B: The strong star property rule, states that a subject that has read and write capabilities can only perform
those functions at the same security level; nothing higher and nothing lower. So, for a subject to be able to read
and write to an object, the clearance and classification must be equal. This is not the access control model
property that prevented APFEL from reading FIGCO’s cargo information.
C: Polymorphism takes place when different objects respond to the same command, input, or message in
different ways. This is not the secure database technique used in this question.

Harris, Shon, All In One CISSP Exam Guide, 4th Edition, McGraw-Hill, New York, 2007, pp. 370, 1186


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