Effective CISSP Questions

Your organization implemented a database that allows multiple tuples in a relation sharing the same primary key and distinguished by their security levels. Which of the following is the primary security objective for the implementation?
A. Confidentiality
B. Integrity
C. Availability
D. Non-repudiation

Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.

My suggested answer is A. Confidentiality.

Polyinstantiation is a DBMS specific security issue, which “allows a relation to contain multiple rows with the same primary key; the multiple instances are distinguished by their security levels.” (NIST SP 800-8) A row in a table (relation) is also known as a tuple.

RDBMS - Table
RDBMS – Table

Depending on the security level established, one record contains sensitive information, and the other one does not, that is, a user will see the record’s information depending on his/her level of confidentiality previously dictated by the company’s policy.

Source: Wikipedia


Polyinstantiation is frequently used with mandatory access control database systems
to control inference. The following is an excerpt from NIST SP 800-8, Security Issues in the Database Language SQL:

  • Inference: Derivation of new information from known information. The inference problem refers to the fact that the derived information may be classified at a level for which the user is not cleared. The inference problem is that of users deducing unauthorized information from the legitimate information they acquire.
  • Aggregation: The result of assembling or combining distinct units of data when handling sensitive information. Aggregation of data at one sensitivity level may result in the total data being designated at a higher sensitivity level.
  • Polyinstantiation: Polyinstantiation allows a relation to contain multiple rows with the same primary key; the multiple instances are distinguished by their security levels. [SFD92)
  • Referential integrity: A database has referential integrity if all foreign keys reference existing primary keys.
  • Entity integrity: A tuple in a relation cannot have a null value for any of the primary key attributes.
  • Granularity: The degree to which access to objects can be restricted. Granularity can be applied to both the actions allowable on objects, as well as to the users allowed to perform those actions on the object.



My new book, The Effective CISSP: Security and Risk Management, helps CISSP aspirants build a solid conceptual security model. It is not only a tutorial for information security but also a study guide for the CISSP exam and an informative reference for security professionals.

您的組織建置了一個數據庫,該數據庫允許關聯(relation)中的多個元組(tuple)共享相同的主鍵(primary key),並按其安全級別(security level)進行區分。 以下哪個是該建置要達成的主要安全目標?
A. 機密性
B. 完整性
C. 可用性
D. 不可否認性

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