A FIREWALL MODEL OF FILE SYSTEM SECURITY

File system security is fundamental to the security of UNIX and Linux systems since in these systems almost everything is in the form of a file. To protect the system files and other sensitive user files from unauthorized accesses, certain security schemes are chosen and used by different organizations in their computer systems. A file system security model provides a formal description of a protection system. Each security model is associated with specified security policies which focus on one or more of the security principles: confidentiality, integrity and availability. The security policy is not only about “who” can access an object, but also about “how” a subject can access an object. To enforce the security policies, each access request is checked against the specified policies to decide whether it is allowed or rejected. The current protection schemes in UNIX/Linux systems focus on the access control. Besides the basic access control scheme of the system itself, which includes permission bits, setuid and seteuid mechanism and the root, there are other protection models, such as Capabilities, Domain Type Enforcement (DTE) and Role-Based Access Control (RBAC), supported and used in certain organizations. These models protect the confidentiality of the data directly. The integrity of the data is protected indirectly by only allowing trusted users to operate on the objects. The access control decisions of these models depend on either the identity of the user or the attributes of the process the user can execute, and the attributes of the objects. Adoption of these sophisticated models has been slow; this is likely due to the enormous complexity of specifying controls over a large file system and the need for system administrators to learn a new paradigm for file protection. We propose a new security model: file system firewall. It is an adoption of the familiar network firewall protection model, used to control the data that flows between networked computers, toward file system protection. This model can support decisions of access control based on any system generated attributes about the access requests, e.g., time of day. The access control decisions are not on one entity, such as the account in traditional discretionary access control or the domain name in DTE. In file system firewall, the access decisions are made upon situations on multiple entities. A situation is programmable with predicates on the attributes of subject, object and the system. File system firewall specifies the appropriate actions on these situations. We implemented the prototype of file system firewall on SUSE Linux. Preliminary results of performance tests on the prototype indicate that the runtime overhead is acceptable. We compared file system firewall with TE in SELinux to show that firewall model can accommodate many other access control models. Finally, we show the ease of use of firewall model. When firewall system is restricted to specified part of the system, all the other resources are not affected. This enables a relatively smooth adoption. This fact and that it is a familiar model to system administrators will facilitate adoption and correct use. The user study we conducted on traditional UNIX access control, SELinux and file system firewall confirmed that. The beginner users found it easier to use and faster to learn then traditional UNIX access control scheme and SELinux

Dynamic trust negotiation for decentralised e-health collaborations

In the Internet-age, the geographical boundaries that have previously impinged upon inter-organisational collaborations have become decreasingly important. Of more importance for such collaborations is the notion and subsequent nature of security and trust - this is especially so in open collaborative environments like the Grid where resources can be both made available, subsequently accessed and used by remote users from a multitude of institutions with a variety of different privileges spanning across the collaboration. In this context, the ability to dynamically negotiate and subsequently enforce security policies driven by various levels of inter-organisational trust is essential. Numerous access control solutions exist today to address aspects of inter-organisational security. These include the use of centralised access control lists where all collaborating partners negotiate and agree on privileges required to access shared resources. Other solutions involve delegating aspects of access right management to trusted remote individuals in assigning privileges to their (remote) users. These solutions typically entail negotiations and delegations which are constrained by organisations, people and the static rules they impose. Such constraints often result in a lack of flexibility in what has been agreed; difficulties in reaching agreement, or once established, in subsequently maintaining these agreements. Furthermore, these solutions often reduce the autonomous capacity of collaborating organisations because of the need to satisfy collaborating partners demands. This can result in increased security risks or reducing the granularity of security policies. Underpinning this is the issue of trust. Specifically trust realisation between organisations, between individuals, and/or between entities or systems that are present in multi-domain authorities. Trust negotiation is one approach that allows and supports trust realisation. The thesis introduces a novel model called dynamic trust negotiation (DTN) that supports n-tier negotiation hops for trust realisation in multi-domain collaborative environments with specific focus on e-Health environments. DTN describes how trust pathways can be discovered and subsequently how remote security credentials can be mapped to local security credentials through trust contracts, thereby bridging the gap that makes decentralised security policies difficult to define and enforce. Furthermore, DTN shows how n-tier negotiation hops can limit the disclosure of access control policies and how semantic issues that exist with security attributes in decentralised environments can be reduced. The thesis presents the results from the application of DTN to various clinical trials and the implementation of DTN to Virtual Organisation for Trials of Epidemiological Studies (VOTES). The thesis concludes that DTN can address the issue of realising and establishing trust between systems or agents within the e-Health domain, such as the clinical trials domain

An Overview of Automotive Service-Oriented Architectures and Implications for Security Countermeasures

New requirements from the customers\u27 and manufacturers\u27 point of view such as adding new software functions during the product life cycle require a transformed architecture design for future vehicles. The paradigm of signal-oriented communication established for many years will increasingly be replaced by service-oriented approaches in order to increase the update and upgrade capability. In this article, we provide an overview of current protocols and communication patterns for automotive architectures based on the service-oriented architecture (SOA) paradigm and compare them with signal-oriented approaches. Resulting challenges and opportunities of SOAs with respect to information security are outlined and discussed. For this purpose, we explain different security countermeasures and present a state of the section of automotive approaches in the fields of firewalls, Intrusion Detection Systems (IDSs) and Identity and Access Management (IAM). Our final discussion is based on an exemplary hybrid architecture (signal- and service-oriented) and examines the adaptation of existing security measures as well as their specific security features