A secure open system?

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

Mobile security has become increasingly important in mobile computing, hence mandatory access control (MAC) systems have been widely used to protect it. However, malicious code in the mobile system may have significantly impact to the integrity of these MAC systems by forcing them to make the wrong access control decision, because they are running on the same privilege level and memory address space. Therefore, for a trusted MAC system, it is desired to be isolated from the malicious mobile system at runtime. In this paper, we propose a trusted MAC isolation framework called T-MAC to solve this problem. T-Mac puts the MAC system into the enclave provided by the ARM TrustZone so as to avert the direct impact of the malicious code on the access decision process. In the meanwhile, T-MAC provides a MAC supplicant client which runs in the mobile system kernel to effectively lookup policy decisions made by the back-end MAC service in the enclave and to enforce these rules on the system with trustworthy behaviors. Moreover, to protect T-MAC components that are not in the enclave, we not only provide a protection mechanism that enables TrustZone to protect the specific memory region from the compromised system, but establish a secure communication channel between the mobile system and the enclave as well. The prototype is based on SELinux, which is the widely used MAC system, and the base of SEAndroid. The experimental results show that SELinux receives enough protection, and the performance degradation that ranges between 0.53% to 7.34% compared to the original by employing T-MAC.

ABSTRACTSome specific information or resources only can be accessed by authorized users. Discretionary access control (DAC), mandatory access control (MAC), and role‐based access control (RBAC) are three main classes of access control policies. MAC and RBAC are more secure than discretionary access control because a system instead of an object's owner determines the policy. MAC is appropriate for multilevel applications with high security requirements such as military ones, while RBAC provides security and business benefits. Most institutions, companies, and governments are multilevel, so relationships between roles or security levels tend to be hierarchical. In this work, an access control mechanism, providing explicit transitive exception and antisymmetric arrangement, is proposed to provide flexible and appropriate solutions to hierarchical relationships. For practicability, no access control policy is strictly constrained in the proposed mechanism such that security classes can be determined according to specific requirements. The proposed mechanism employs an elliptic curve cryptosystem and a two‐layer hash approach to ensure security and computation efficiency. Copyright © 2014 John Wiley & Sons, Ltd.

An access control system is a collection of rules used to restrict the visibility, access, and usage of the data resources in an institutional environment. When implemented, these rules provide a policy for achieving the security of the institution, establishing a hierarchy of the employees depending on their rights over the institution’s data resouces. An access control system is based on two fundamental concepts: authentication (that verifyies the user's identity) and authorization (that provides a hierarchy of the employees according to their access rights over the institutional resources). Among the most commonly used access control models we recall Role-Based Access Control (RBAC), in which users with the same role have equal access rights to data resources, Discretionary Access Control (DAC), in which the system owner decides which user has access to system resources, and Mandatory Access Control (MAC), in which a series of rules, with a high level of security established by a predefined authority, are used. In this article, we will study the last two models, namely DAC and MAC, along with their main implementations: Access Control Matrix and the Take-Grant models for DAC, BIBA and Bell-LaPadula for MAC.

Role-based access control (RBAC) is a promising alternative to traditional discretionary access control (DAC) and mandatory access control (MAC). The central idea of RBAC is that permissions are associated with roles, and users are made members of appropriate roles thereby acquiring the roles’ permissions. RBAC is policy neutral in that the precise policy being enforced is a consequence of how various components of RBACsuch as role hierarchies, constraints and administration of user-role and role-permission assignment-are configured. This raises the important question as to whether RBAC is sufficiently powerful to simulate DAC and MAC. Simulation of MAC in RBAC has been demonstrated earlier by Nyanchama and Osborn and by Sandhu. In this paper we demonstrate how to simulate several variations of DAC in RBAC, using the wellknown RBAC96 model of Sandhu et al. In combination with earlier work we conclude that RBAC encompasses both MAC and DAC.

Access control is generally a rule or procedure that allows, denies, restricts or limit access to system's resources. It may, as well, monitor and record all attempts made to access a system. Access Control may also identify users attempting to access unauthorized resources. It is a mechanism which is very much important for protection in computer security. Various access control models are in use, including the most common Mandatory Access Control (MAC), Discretionary Access Control (DAC) and Role Based Access Control (RBAC). All these models are known as identity based access control models. In all these access control models, user (subjects) and resources (objects) are identified by unique names. Identification may be done directly or through roles assigned to the subjects. These access control methods are effective in unchangeable distributed system, where there are only a set of Users with a known set of services. For this reason, we propose a framework which is well suited to many situations in cloud computing where users or applications can be clearly separated according to their job functions. In this chapter, we proposes a role based access control framework with various features including security of sensitive data, authorization policy and secure data from hackers. Our proposed role based access control algorithm provides tailored and fine level of user access control services without adding complexity, and supports access privileges updates dynamically when a user's role is added or updated.

Access control is a security technique that specifies which users can access particular resources in a computing environment. Over the years, numerous access control models have been developed to address various aspects of computer security. In this paper, we focus on a modern approach, attribute-based access control (ABAC), which has been proposed in order to overcome limitations of traditional models: discretionary access control (DAC), mandatory access control (MAC) and role-based access control (RBAC). The work on integrating access control mechanisms in semantic web technologies is developing into two directions: (1) to use semantic web technologies for modeling and analyzing access control policies and (2) to protect knowledge encoded in an ontology. In this paper we focus on the first issue and investigate how ABAC can be integrated into ontology languages.

With the increasingly strict requirement for computer system security, access control models have become more complex. Existing models, such as discretionary access control (DAC) model, mandatory access control (MAC) model, role based access control (RBAC) model, and attribute based access control (ABAC) model, all have advantages and disadvantages regarding practicability and security. In addition, there is an inherent security risk in these access control models. The models merely control the access permission, but ignore the verification for the identity credibility of the entities involved in the access. With the proposal of trusted computing and the application of trusted platform, it is possible to implement, on stand-alone computers, the verification of identity credibility for the entities involved in the access. In this paper, we analyze the authorization and access decision policy of the RBAC model and the ABAC model. The characteristics of the trusted computing, which can ensure the identity credibility of the entities involved in the access, is also considered. Based on the above analysis, we establish a trusted computing based enhanced access control (TCBEAC) model, which can be deployed on stand-alone computers for common users.

Role-based access control (RBAC) is useful in information security. It is a super set of discretionary access control (DAC) and mandatory access control (MAC). Since DAC and MAC are useful in information flow control (which protects privacy within an application), RBAC can certainly be used in that control. Our research reveals that different control granularity is needed in different cases when controlling information flows within an application. An information flow control model should thus simultaneously offer different levels of control granularity. We designed a multipleleveled RBAC model to offer multiple levels of control granularity, in which a level of RBAC controls a level of granularity. We called the model L n RBAC (n-leveled RBAC), which offer the following features: (1) it allows different control granularity in different cases, (2) it solves the covert channel problems caused by abnormal program stopping, (3) it adapts to dynamic object state change, (4) it controls method invocation through argument sensitivity (5) it allows purpose-oriented method invocation, (6) it controls write access precisely, and (7) it avoids Trojan horses. We implemented a prototype for L n RBAC and evaluated it. This paper presents L n RBACL.

With the use of virtualization, threats appears gradually in domains constituted by host and virtual machines (VMs). Access control between VMs becomes a necessary method of the security management of virtualized platform. The traditional Mandatory Access Control (MAC) based on fixed security policy is greatly restricted on flexibility. In this paper, we proposed a quantitatively trust evaluation method based on VM's historical behavior, which combined with existing MAC mechanism, to build a flexible, fine-grained access control mechanism.

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.

Enforcing a practical Mandatory Access Control (MAC) in a commercial operating system to tackle malware problem is a grand challenge but also a promising approach. The firmest barriers to apply MAC to defeat malware programs are the incompatible and unusable problems in existing MAC systems. To address these issues, we start our work by analyzing the technical details of 2,600 malware samples one by one and performing experiments over two types of MAC enforced operating systems. Based on the preliminary studies, we design a novel MAC model incorporating intrusion detection and tracing in a commercial operating system, named Tracer, in order to disable malware on hosts while offering good compatibility to existing software and good usability to common users who are not system experts. The model conceptually consists of three actions: detecting, tracing and restricting suspected intruders. One novelty is that it leverages light-weight intrusion detection and tracing techniques to automate security label configuration that is widely acknowledged as a tough issue when applying a MAC system in practice. The other is that, rather than restricting information flow as a traditional MAC does, it traces intruders and restricts only their critical malware behaviors, where intruders represent processes and executables that are potential agents of a remote attacker. Our prototyping and experiments on Windows show that Tracer can effectively defeat all malware samples tested via blocking malware behaviors while not causing a significant compatibility problem.

Formal Description of Trust-based Access Control

Mandatory access control is an important technology to achieve security-enhanced operating system, and access control policy is core to Mandatory Access Control. The security policy generation tool is given by current mainstream of mandatory access control system, while it is lack of assessment of effectiveness of security policies. This paper analyzes the implementation method of mandatory access control based on LSM, proposes a solution based on system calls to evaluate validity of mandatory access control policy, outlines its concrete realization and verifies its effectiveness from a practical view.

Cloud Computing is the fast growing and the dominant field of Information Technology (IT) industry. It proposes on demand and cost effective services such as Software as a Service (SaaS), Platform as a Service (PaaS) and Infrastructure as a Service (IaaS). Many security challenges are drawn from these services in cloud environment such as abuse of cloud services, data security, malicious insider and cyber-attacks. Although various access control policies and models such as Mandatory Access Control (MAC) and Role Based Access Control (RBAC) are existing, but these are not suitable for Cloud access control requirements.