RI # 102 - User Attributes to be Bound Should be Specified

Type: Editorial/Grammatical Change Source: US NI Date: 06/02/2000
Status: Discussion Source #: IWG #0351
CC Part #1 Reference:
CC Part #2 Reference: CC Part 2, Annex G.6 (FIA_USB)
CC Part #3 Reference:
CEM Reference:
Reason: National Interpretation
Problem:

At the time a PP/ST is developed, the PP/ST author knows the significant attributes of the FSPs of the TOE, and which of those attributes are to be derived from user-based information. Thus, it is possible for the PP/ST author to know which user attributes are to be bound to subjects created on the user's behalf. However, there is no way to specify such in the PP/ST.

Proposed Solution:

In order to address this interpretation, the following changes should be made to FIA_USB.1.1: FIA_USB.1.1: The TSF shall associate the following user security attributes with subjects acting on behalf of that user: [assignment: list of user security attributes to be bound].

However, in CC v2.1, the words of the FIA_USB.1.1 element use the word "appropriate". In order to specify the specific attributes to be bound, the PP/ST author must refine the element, and the evaluator must determine if the specified attributes are indeed "appropriate"; further, the evaluator must determine if there are appropriate attributes not included in the refined element. This creates a risk of inconsistent evaluator interpretation. The ideal approach is to replace the need for refinement with an explicit assignment. The assignment should be driven by the attributes that are needed to enforce the TSP. For example, an access control policy based on user identity would require the user identity information be bound to the subject. This interpretation should be distinguished from IWG #0353 and IWG #0354, which discuss the security attributes bound to subjects, for not all subject security attributes derive from user attributes.