Access Control Policies, Models, and Mechanisms

Chapter 23 - Policies, Access Control, and Formal Methods

The Pi-calculus has been developed to reason about behavioural equivalence. Different notions of equivalence are defined in terms of process interactions, as well as the context of processes. There are various extensions of the Pi-calculus, such as the SPI calculus, which has primitives to facilitate security protocol design.<br /> <br />Another area of computer security is access control research, which includes problems of access control models, policies and access control mechanism. The design of a unified framework for access control requires that all policies are supported and different access control models are instantiated correctly.<br /> <br />In this paper we will utilise the Pi calculus to reason about access control policies and mechanism. An equivalence of different policy implementations, as well as access control mechanism will be shown. Finally some experiences regarding the use of Pi-calculus are presented.

Access control is the process of mediating every request to resources and data maintained by a system and determining whether the request should be granted or denied. The access control decision is enforced by a mechanism implementing regulations established by a security policy. Different access control policies can be applied, corresponding to different criteria for defining what should, and what should not, be allowed, and, in some sense, to different definitions of what ensuring security means. In this chapter we investigate the basic concepts behind access control design and enforcement, and point out different security requirements that may need to be taken into consideration. We discuss several access control policies, and models formalizing them, that have been proposed in the literature or that are currently under investigation.

Traditional access control mechanisms prevent illegal access by controlling access right before executing an action; they belong to a class of a priori security solutions and, from this point of view, they have some limitations, like inflexibility in unanticipated circumstances. By contrast, a posteriori mechanisms enforce policies not by preventing unauthorized access, but rather by deterring it. Such access control needs evidence to prove violations. Evidence is derived from one or several log records, which trace each user's actions. Efficiency of violation detection mostly depends on the compliance of log records with the access control policy. In order to develop an efficient method for finding these violations, we propose restructuring log records according to a security policy model. We illustrate our methodology by applying it to the healthcare domain, taking care of the IHE (Integrating the healthcare enterprise) framework, particularly its basic security profile, ATNA (Audit Trail and Node Authentication). This profile defines log records established on the analysis of common health practice scenarios. We analyze and establish how ATNA log records can be refined in order to be integrated into an a posteriori access and usage control process, based on an expressive and contextual security policy like the OrBAC policy.

Access control (AC) is a computer security requirement used to control, in a computing environment, what the user can access, when and how. Policy administration is an essential feature of an AC system. As the number of computers are in hundreds of millions, and due to the different organization requirements, applications and needs, various AC models are presented in literature, such as: Discretionary Access Control (DAC), Mandatory Access Control (MAC), Role Based Access Control (RBAC), etc. These models are used to implement organizational policies that prevent the unauthorized disclosure of sensitive data, protecting the data integrity, and enabling secure access and sharing of information. Each AC model has its own methods for making AC decisions and policy enforcement. However, due to the diversity of AC models and the various concerns and restrictions, its essential to find AC metamodels with higher level of abstraction. Access control metamodels serve as a unifying framework for specifying any AC policy and should ease the migration from an AC model to another. This study reviews existing works on metamodels descriptions and representations. But, are the presented metamodels sufficient to handle the needed target of controlling access especially in the presence of the current information technologies? Do they encompass all features of other AC models? In this paper we are presenting a survey on AC metamodels.

Cloud computing offers cost effective services on-demand which encourage critical infrastructure providers to consider migrating to the cloud. Critical infrastructures are considered as a backbone of modern societies such as power plants and water. Information in cloud computing is likely to be shared among different entities, which could have various degrees of sensitivity. This requires robust isolation and access control mechanisms. Although various access control models and policies have been developed, they cannot fulfil requirements for a cloud based access control system. The reason is that cloud computing has a diverse sets of security requirements and unique security challenges such as multi-tenant and heterogeneity of security policies, rules and domains. This thesis provides a detailed study of cloud computing security challenges and threats, which were used to identify security requirements for various critical infrastructure providers. We found that an access control system is a crucial security requirement for the surveyed critical infrastructure providers. Furthermore, the requirement analysis was used to propose a new criteria to evaluate access control systems for cloud computing. Moreover, this work presents a new cloud based access control model to meet the identified cloud access control requirements. The model does not only ensure the secure sharing of resources among potential untrusted tenants, but also has the capacity to support different access permissions for the same cloud user. Our focused in the proposed model is the lack of data isolation in lower levels (CPU caches), which could lead to bypass access control models to gain some sensitive information by using cache side-channel attacks. Therefore, the thesis investigates various real attack scenarios and the gaps in existing mitigation approaches. It presents a new Prime and Probe cache side-channel attack, which can give detailed information about addresses accessed by a virtual machine with no need for any information about cache sets accessed by the virtual machine. The design, implementation and evaluation of a proposed solution preventing cache side-channel attacks are also presented in the thesis. It is a new lightweight solution, which introduces very low overhead (less than 15,000 CPU cycles). It can be applied in any operating system and prevents cache side-channel attacks in cloud computing. The thesis also presents a new detecting cache side-channel attacks solution. It focuses on the infrastructure used to host cloud computing tenants by counting cache misses caused by a virtual machine. The detection solutions has 0% false negative and 15% false positive.

Elisa Bertino, Sushil Jajodia, and Pierangela Samarati Although there are several choices of policies for protection of information, access control models have been developed for a fixed set pre-defined access control policies that are then built into the corresponding access control mechanisms. This becomes a problem, however, if the access control requirements of an application are different from the policies built into a mechanism. In most cases, the only solution is to enforce the requirements as part of the application code, but this makes verification, modification, and adequate enforcement of these policies impossible. In this paper, we propose a flexible authorization mechanism that can support different security policies. The mechanism enforces a general authorization model onto which multiple access control policies can be mapped. The model permits negative and positive authorizations, authorizations that must be strongly obeyed and authorizations that allow for exceptions, and enforces ownership together with delegation of administrative privileges.

A Virtual Organization (VO) consists of some real organizations with common interests, which aims to provide inter organizational associations to reach some common goals by sharing their resources with each other. Providing security mechanisms, and especially a suitable access control mechanism, which enforces the defined security policy is a necessary requirement in VOs. Since VO is a complex environment with the huge number of users and resources, traditional access control models cannot satisfy VOs security requirements. Most of the current proposals are basically based on the attributes of users and resources. In this paper, we suggest using a combination of the semantic based access control (SBAC) model, and the attribute based access control (ABAC) model with the shared ontology of subjects' attributes in VOs. In this model, each participating organization makes its access control decisions according to an enhanced model of the ABAC model. However, access decision in the VO is made in more abstract level through an enhanced model of theSBACmodel. Using the ontology of users and resources in this model facilitates access control in large scale VOs with numerous organizations. By the combination ofSBACand ABAC, we attain their benefits and eliminate their shortcomings. In order to show the applicability of the proposed model, an access control system, based on the proposed model, has been implemented in Java using available APIs, including Sun's XACML API, Jena, Pellet, and Protege.

PurposeThis paper aims to manage access control tasks to satisfy the user privacy needs of online information resources according to social relations and tags.Design/methodology/approachThe study proposes a method for access control management in the online social context. The proposed method includes the access control policy management process, metadata of access control policies, the data of ontologies, tags, and social relations, and conflict detection rules.FindingsOnline information sharing and hiding, which needs to consider social relations and mentioned topics, is a unique context and needs a novel access control mechanism. Ontologies are powerful and expressive enough to identify conflicts in access control policies. The paper provides a method using ontologies to control the access control activities based on social relations and tags on web content. The effectiveness of the method's conflict detection rules is validated through several scenarios.Research limitations/implicationsTo make the proposed method suitable for widespread usage, further work is required to develop an access control policy specification and conflict detection tool. The proposed method introduces relatively novel usage scenarios, which consider social relationships, and tags compared with existing access control methods for online information sharing.Practical implicationsThe proposed access control mechanism can be integrated into existing web sites. Online users can use this method to share information more easily than at present.Originality/valueThe method enables flexible access control in social contexts and handles unavoidable conflicts. It also opens the way to new access control scenarios in online social activities. The method can be used to keep secrets hidden from selected people.

Towards more pro-active access control in computer systems and networks

The access control is a mechanism that a system grants, revoke the right to access the object. The subject and object can able to integrate, synchronize, communicate and optimize through read, write and execute over a UFS. The access control mechanism is the process of mediating each and every request to system resources, application and data maintained by a operating system and determining whether the request should be approve, created, granted or denied as per top management policy. The AC mechanism, management and decision is enforced by implementing regulations established by a security policy. The management has to investigate the basic concepts behind access control design and enforcement, point out different security requirements that may need to be taken into consideration. The authors have to formulate and implement several ACM on normalizing and optimizing them step by step, that have been highlighted in proposed model for development and production purpose. This research paper contributes to the development of an optimization model that aims and objective to determine the optimal cost, time and maximize the quality of services to be invested into security model and mechanisms deciding on the measure components of UFS. This model has to apply to ACM utilities over a Web portal server on object oriented and distributed environment. This ACM will be resolve the uncertainty, un-order, un formal and unset up (U^4) problems of web portal on right time and right place of any where & any time in around the globe. It will be more measurable and accountable for performance, fault tolerance, throughput, bench marking and risk assessment on any application.

The access control is a mechanism that a system grants, revoke the right to access the object. The subject and object can able to integrate, synchronize, communicate and optimize through read, write and execute over a UFS. The access control mechanism is the process of mediating each and every request to system resources, application and data maintained by a operating system and determining whether the request should be approve, created, granted or denied as per top management policy. The AC mechanism, management and decision is enforced by implementing regulations established by a security policy. The management has to investigate the basic concepts behind access control design and enforcement, point out different security requirements that may need to be taken into consideration. The authors have to formulate and implement several ACM on normalizing and optimizing them step by step, that have been highlighted in proposed model for development and production purpose. This research paper contributes to the development of an optimization model that aims and objective to determine the optimal cost, time and maximize the quality of services to be invested into security model and mechanisms deciding on the measure components of UFS. This model has to apply to ACM utilities over a Web portal server on object oriented and distributed environment. This ACM will be resolve the uncertainty, un-order, un formal and unset up (U^4) problems of web portal on right time and right place of any where & any time in around the globe. It will be more measurable and accountable for performance, fault tolerance, throughput, bench marking and risk assessment on any application.

We propose formal analysis of access control policies associated with business processes. Formal analysis of such policies enables us to investigate certain properties of interest and determine whether they hold. Discovering whether these policies create the intended effects, especially when the number of policies is increased and often composed, can become complex. In addition, we believe that access control policies must be specified in such a way that their integration into business processes is straightforward. Prior research has focused on formal verification of either access control policies or business processes but not viewed the two as an integrated whole. We show an approach in which access control policies and business processes are described using the same foundational building blocks, consequently, integration of access control policies and business processes is significantly less complex. Furthermore, access control policies can now be described by business patterns, and this description may result in discovery of access control patterns that can be used in the future. Finally, our approach through the use of business patterns is capable of modeling access control policies in the same way an access control model does. In addition, these policies can be specified and extended using rules, and in this respect, are akin to a policy language.

Healthcare information systems deal with sensitive data across complex workflows. They often allow various stakeholders from different environments to access data across organizational boundaries. This elevates the risk of exposing sensitive healthcare information to unauthorized personnel, leading ‘controlling access to resources' a major concern. To prevent unwanted access to sensitive information, healthcare organizations need to adopt effective workflows and access control mechanisms. Many healthcare organizations are not yet considering or do not know how to accommodate the ‘context' element as a crucial element in their workflows and access control policies. The authors envision the future of healthcare where ‘context' will be considered as a crucial element. They can accommodate context through a new element ‘environment' in workflows, and can accommodate context in policies through well-known attribute based access control mechanism (ABAC). This research mainly addresses these problems by proposing a model to integrate workflows and access control policies and thereby identifying workflow activities that are not being protected by access control policies and improving the workflow activities and/or existing access control policies using SARE (Subject, Action, Resource, and environment) elements.

Healthcare information systems deal with sensitive data across complex workflows. They often allow various stakeholders from different environments to access data across organizational boundaries. This elevates the risk of exposing sensitive healthcare information to unauthorized personnel, leading ‘controlling access to resources' a major concern. To prevent unwanted access to sensitive information, healthcare organizations need to adopt effective workflows and access control mechanisms. Many healthcare organizations are not yet considering or do not know how to accommodate the ‘context' element as a crucial element in their workflows and access control policies. The authors envision the future of healthcare where ‘context' will be considered as a crucial element. They can accommodate context through a new element ‘environment' in workflows, and can accommodate context in policies through well-known attribute based access control mechanism (ABAC). This research mainly addresses these problems by proposing a model to integrate workflows and access control policies and thereby identifying workflow activities that are not being protected by access control policies and improving the workflow activities and/or existing access control policies using SARE (Subject, Action, Resource, and environment) elements.