The (star) Integrity Axiom in the Biba Model

D.

The(star) integrity axiom of the Biba access control model states that an object at one level of integrity is not permitted to modify an object of a higher level of integrity (no write up)

Source: KRUTZ, Ronald L.

& VINES, Russel.

D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 5: Security Architectures and Models (page 205).

The Biba model is a security model that is used to ensure the integrity of information. The model was developed by Ken Biba in the 1970s and is based on a set of axioms that define how information can be accessed and modified.

The integrity axiom is one of the three axioms in the Biba model. This axiom states that "no subject at a given level of integrity may read data from a subject at a lower level of integrity." In other words, information can only flow in one direction, from a higher level of integrity to a lower level of integrity.

This axiom is important because it helps to prevent information from being compromised by ensuring that information at a higher level of integrity is not contaminated by information from a lower level of integrity. For example, if a highly sensitive document is stored on a computer that is also used for web browsing, the integrity axiom ensures that any information obtained from the web cannot compromise the integrity of the sensitive document.

In terms of the answer choices given, option D ("No write up") is incorrect because it does not relate to the integrity axiom. The correct answer is option C ("No read down"), which accurately describes the integrity axiom in the Biba model.