Nomad: A Security Model with Non Atomic Actions and Deadlines

Abstract

Modelling security policies requires means to specify permissions and prohibitions. However, this is generally not sufficient to express security properties such as availability and obligations must be also considered. By contrast to permissions and prohibitions, obligations are often associated with deadlines to specify bounded time availability requirements. In this case, a violation only occurs if the obliged action is not performed before the deadline. On the other hand, when specifying high level security policies, it is convenient to consider abstract non atomic actions. Since most access control mechanisms only deal with atomic actions such as read or write, these non atomic actions must be decomposed into more basic ones. In this paper, we define a formal security model called Nomad to express privileges on non atomic actions. This model combines deontic and temporal logics. In Nomad, we model conditional privileges and obligations with deadlines. We also formally analyze how privileges on non atomic actions can be decomposed into more basic privileges on elementary actions.

Test Generation for Network Security Rules

“…However, it is clear that this formalism may be not sufficient to deal with arbitrary security rules, and that more specific operator/modalities need to be considered. One can think for instance of a triggered obligation bounded by an event (and not by an arbitrary timeout), or of some of the general operators proposed in the Nomad logic [3]. Further work remains to be done in order to check which of these operators could be supported by our tile-based approach.…”

“…2 There should be no user account on relays placed in the DMZ. 3 Mailbox servers containing user accounts should be in the private zone. There could be as many of these servers as necessary.…”

A Guided Web Service Security Testing Method

“…Bellow, we recall a part of the Nomad grammar. The complete definition of the Nomad language can be found in Cuppens et al (2005).…”

“…Each criterion can be also modelled formally by means of security rules written with languages such as XACML (eXtensible Access Control Markup Language OASIS standards organization (2009)), Nomad (Security Model with Non Atomic Actions and Deadlines Cuppens et al (2005)), or OrBAC (Organisation-based access control Kalam et al (2003)). …”

“…Several security rule languages have been introduced in Cuppens et al (2005); Senn et al (2005). We have chosen Nomad (Non atomic actions and deadlines Cuppens et al (2005)) to model abstract test patterns which can be directly derived from an existing security rule set. Nomad is well suited for expressing properties such as permissions, prohibitions or obligations and 11 www.intechopen.com is able to take into account response delays.…”