Achieving Security Assurance with Assertion-based Application Construction

abstract: Modern software applications are commonly built by leveraging pre-fabricated modules, e.g. application programming interfaces (APIs), which are essential to implement the desired functionalities of software applications, helping reduce the overall development costs and time. When APIs deal with security-related functionality, it is critical to ensure they comply with their design requirements since otherwise unexpected flaws and vulnerabilities may consequently occur. Often, such APIs may lack sufficient specification details, or may implement a semantically-different version of a desired security model to enforce, thus possibly complicating the runtime enforcement of security properties and making it harder to minimize the existence of serious vulnerabilities. This paper proposes a novel approach to address such a critical challenge by leveraging the notion of software assertions. We focus on security requirements in role-based access control models and show how proper verification at the source-code level can be performed with our proposed approach as well as with automated state-of-the-art assertion-based techniques.The final version of this article, as published in EAI Endorsed Transactions on Collaborative Computing, can be viewed online at: http://eudl.eu/doi/10.4108/eai.21-12-2015.15081

Vérification et validation de politiques de contrôle d'accès dans le domaine médical

Dans le domaine médical, la numérisation des documents et l’utilisation des dossiers patient électroniques (DPE, ou en anglais EHR pour Electronic Health Record) offrent de nombreux avantages, tels que la facilité de recherche et de transmission de ces données. Les systèmes informatiques doivent reprendre ainsi progressivement le rôle traditionnellement tenu par les archivistes, rôle qui comprenait notamment la gestion des accès à ces données sensibles. Ces derniers doivent en effet être rigoureusement contrôlés pour tenir compte des souhaits de confidentialité des patients, des règles des établissements et de la législation en vigueur. SGAC, ou Solution de Gestion Automatisée du Consentement, a pour but de fournir une solution dans laquelle l’accès aux données du patient serait non seulement basée sur les règles mises en place par le patient lui-même mais aussi sur le règlement de l’établissement et sur la législation. Cependant, cette liberté octroyée au patient est source de divers problèmes : conflits, masquage des données nécessaires aux soins ou encore tout simplement erreurs de saisie. Pour effectuer ces vérifications, les méthodes formelles fournissent des moyens fiables de vérification de propriétés tels que les preuves ou la vérification de modèles. Cette thèse propose des méthodes de vérification adaptées à SGAC pour le patient : elle introduit le modèle formel de SGAC, des méthodes de vérifications de propriétés. Afin de mener ces vérifications de manière automatisée, SGAC est modélisé en B et Alloy ; ces différentes modélisations donnent accès aux outils Alloy et ProB, et ainsi à la vérification automatisée de propriétés via la vérification de modèles ou model checking.Abstract : In healthcare, data digitization and the use of the Electronic Health Records (EHR) offer several benefits, such as the reduction of the space occupied by data, or the ease of data search or data exchanges. IT systems must gradually take up the archivist’s role by managing the accesses over sensitive data, which have to be compliant with patient wishes, hospital rules, as well as laws and regulations. SGAC, or Solution de Gestion Automatisée du Consentement (Automated Consent Management Solution), aims to provide a solution in which access to patient data would be based on patient rules, hospital rules and laws. However, the freedom granted to the patient can cause several problems : conflicts, concealment of crucial data needed to treat the patient adequately, and data-capture errors. Therefore, verification and validation of policies are essential : formal methods provide reliable ways, such as proofs or model checking, to conduct verifications of properties. This thesis provides verification methods applied on SGAC for the patient : it introduces the formal model of SGAC, methods to verify properties such as data access resolution, hidden data detection or redundant rule identification. Modeling of SGAC in B and Alloy provides access to the tools Alloy and ProB, and thus, automated property verification through model checking

A Comprehensive Cloud Security Model with Enhanced Key Management, Access Control and Data Anonymization Features

A disgusting problem in public cloud is to securely share data based on fine grained access control policies and unauthorized key management. Existing approaches to encrypt policies and data with different keys based on public key cryptosystem are Attribute Based Encryption and proxy re-encryption. The weakness behind approaches is: It cannot efficiently handle policy changes and also problem in user revocation and attribute identification.  Even though it is so popular, when employed in cloud it generate high computational and storage cost. More importantly, image encryption is some out complex in case of public key cryptosystem. On the publication of sensitive dataset, it does not preserve privacy of an individual. A direct application of a symmetric key cryptosystem, where users are served based on the policies they satisfy and unique keys are generated by Data Owner (DO). Based on this idea, we formalize a new key management scheme, called Symmetric Chaos Based key Management (SCBKM), and then give a secure construction of a SCBKM scheme called AS-Chaos. The idea is to give some secrets to Key Manager (KM) based on the identity attributes they have and later allow them to derive actual symmetric keys based on their secrets. Using our SCBKM construct, we propose an efficient approach for fine-grained encryption-based access control for data stored in untrusted cloud storage

Adding Privacy Protection to Policy Based Authorisation Systems

An authorisation system determines who is authorised to do what i.e. it assigns privileges to users and provides a decision on whether someone is allowed to perform a requested action on a resource. A traditional authorisation decision system, which is simply called authorisation system or system in the rest of the thesis, provides the decision based on a policy which is usually written by the system administrator. Such a traditional authorisation system is not sufficient to protect privacy of personal data, since users (the data subjects) are usually given a take it or leave it choice to accept the controlling organisation’s policy. Privacy is the ability of the owners or subjects of personal data to control the flow of data about themselves, according to their own preferences. This thesis describes the design of an authorisation system that will provide privacy for personal data by including sticky authorisation policies from the issuers and data subjects, to supplement the authorisation policy of the controlling organisation. As personal data moves from controlling system to controlling system, the sticky policies travel with the data. A number of data protection laws and regulations have been formulated to protect the privacy of individuals. The rights and prohibitions provided by the law need to be enforced by the authorisation system. Hence, the designed authorisation system also includes the authorisation rules from the legislation. This thesis describes the conversion of rules from the EU Data Protection Directive into machine executable rules. Due to the nature of the legislative rules, not all of them could be converted into deterministic machine executable rules, as in several cases human intervention or human judgement is required. This is catered for by allowing the machine rules to be configurable. Since the system includes independent policies from various authorities (law, issuer, data subject and controller) conflicts may arise among the decisions provided by them. Consequently, this thesis describes a dynamic, automated conflict resolution mechanism. Different conflict resolution algorithms are chosen based on the request contexts. As the EU Data Protection Directive allows processing of personal data based on contracts, we designed and implemented a component, Contract Validation Service (ConVS) that can validate an XML based digital contract to allow processing of personal data based on a contract. The authorisation system has been implemented as a web service and the performance of the system is measured, by first deploying it in a single computer and then in a cloud server. Finally the validity of the design and implementation are tested against a number of use cases based on scenarios involving accessing medical data in a health service provider’s system and accessing personal data such as CVs and degree certificates in an employment service provider’s system. The machine computed authorisation decisions are compared to the theoretical decisions to ensure that the system returns the correct decisions

Cybersecurity analysis of a SCADA system under current standards, client requisites, and penetration testing

Supervisory Control and Data Acquisition (SCADA) systems are essential for monitoring and controlling a country's Critical Infrastructures (CI) such as electrical power grids, gas, water supply, and transportation services. These systems used to be mostly isolated and secure, but this is no longer true due to the use of wider and interconnected communication networks to reap benefits such as scalability, reliability, usability, and integration. This architectural change together with the critical importance of these systems made them desirable cyber-attack targets. Just as in other Information Technology (IT) systems, standards and best practices have been developed to provide guidance for SCADA developers to increase the security of their systems against cyber-attacks.With the assistance of EFACEC, this work provides an analysis of a SCADA system under current standards, client requisites, and testing of vulnerabilities in an actual prototype system. Our aim is to provide guidance by example on how to evaluate and improve the security of SCADA systems, using a basic prototype of EFACEC's ScateX# SCADA system, following both a theoretical and practical approach. For the theoretical approach, a list of the most commonly adopted ICS (Industrial Control Systems) and IT standards is compiled, and then sets of a generic client's cybersecurity requisites are analyzed and confronted with the prototype's specifications. A study of the system's architecture is also performed to identify vulnerabilities and non-compliances with both the client's requisites and the standards and, for the identified vulnerabilities, corrective and mitigation measures are suggested. For the practical approach, a threat model was developed to help identify desirable assets on SCADA systems and possible attack vectors that could allow access to such assets. Penetration tests were performed on the prototype in order to validate the attack vectors, to evaluate compliance, and to provide evidence of the effectiveness of the corrective measures

A Dynamic Access Control Model Using Authorising Workfow and Task Role-based Access Control

Access control is fundamental and prerequisite to govern and safeguard information assets within an organisation. Organisations generally use Web enabled remote access coupled with applications access distributed across various networks. These networks face various challenges including increase operational burden and monitoring issues due to the dynamic and complex nature of security policies for access control. The increasingly dynamic nature of collaborations means that in one context a user should have access to sensitive information, whilst not being allowed access in other contexts. The current access control models are static and lack Dynamic Segregation of Duties (SoD), Task instance level of Segregation, and decision making in real time. This thesis addresses these limitations describes tools to support access management in borderless network environments with dynamic SoD capability and real time access control decision making and policy enforcement. This thesis makes three contributions: i) Defining an Authorising Workflow Task Role Based Access Control (AW-TRBAC) using existing task and workflow concepts. This new workflow integrates dynamic SoD, whilst considering task instance restriction to ensure overall access governance and accountability. It enhances existing access control models such as Role Based Access Control (RBAC) by dynamically granting users access rights and providing access governance. ii) Extension of the OASIS standard of XACML policy language to support dynamic access control requirements and enforce access control rules for real time decision making. This mitigates risks relating to access control, such as escalation of privilege in broken access control, and insucient logging and monitoring. iii) The AW-TRBAC model is implemented by extending the open source XACML (Balana) policy engine to demonstrate its applicability to a real industrial use case from a financial institution. The results show that AW-TRBAC is scalable, can process relatively large numbers of complex requests, and meets the requirements of real time access control decision making, governance and mitigating broken access control risk

Architectural Alignment of Access Control Requirements Extracted from Business Processes

Business processes and information systems evolve constantly and affect each other in non-trivial ways. Aligning security requirements between both is a challenging task. This work presents an automated approach to extract access control requirements from business processes with the purpose of transforming them into a) access permissions for role-based access control and b) architectural data flow constraints to identify violations of access control in enterprise application architectures