Management of Exceptions on Access Control Policies

Abstract

Abstract. The use of languages based on positive or negative expressiveness is very common for the deployment of security policies (i.e., deployment of permissions and prohibitions on firewalls through singlehanded positive or negative condition attributes). Although these languages may allow us to specify any policy, the single use of positive or negative statements alone leads to complex configurations when excluding some specific cases of general rules that should always apply. In this paper we survey such a management and study existing solutions, such as ordering of rules and segmentation of condition attributes, in order to settle this lack of expressiveness. We then point out to the necessity of full expressiveness for combining both negative and positive conditions on firewall languages in order to improve this management of exceptions on access control policies. This strategy offers us a more efficient deployment of policies, even using fewer rules.

A System for Timely and Controlled Information Sharing in Emergency Situations

“…Since one of the target scenarios of our system is healthcare, we believe it is interesting to see how our proposal differs from the many existing access control models proposed for this domain (e.g., [5], [4], [2]). The main difference is that these models do not support emergency descriptions and the use of CEP for emergency detection.…”

“…In this case, the arrival of a tuple t such that t:temp ¼ 38 results in the simultaneous creation and deletion of the corresponding emergency and tacp instances. 2 We formally define this problem by showing also the correctness and enforcement in the following sections.…”

Sorting out role based access control

“…We distinguish the set of subjects S (the who), the set of permissions P (the what), and the access relation SP ⊆ S × P (who gets to do what). In Figure 1a this situation is depicted using an entity relationship diagram 1 This very limited conceptual framework suffices in practice only as long as S and P are relatively small sets. If the cardinalities of S and P are too large there are too many pairs in S × P to consider.…”

“…For practitioners this typically means, that, when an exception arises, instead of exercising in transformations of logical expressions and consequent rewriting of existing AC rules, security officers can generalise the exception, and cleanly and compositionally adapt the previous AC specification touching far fewer rules (for very practical examples see [1]). For that matter we shall give an extensive example on how and why negative objects of indirection could work in practice.…”

Strategies for Reducing Risks of Inconsistencies in Access Control Policies

“…For example, MS-Windows firewalls exclusively specify exceptions, since the basic default effect is deny. Optimizing the specification of exceptions has been addressed in [11]. However, in a language with the capability to express complex conditions with multiple ranges in a single rule, the full extensions to language expressiveness that they propose would not be necessary.…”