Model-Based Analysis of Role-Based Access Control

Model-Driven Engineering (MDE) has been extensively studied. Many directions have been explored, sometimes with the dream of providing a fully integrated approach for designers, developers and other stakeholders to create, reason about and modify models representing software systems. Most, but not all, of the research in MDE has focused on general-purpose languages and models, such as Java and UML. Domain-specific and cross-cutting concerns, such as security, are increasingly essential parts of a software system, but are only treated as second-class citizens in the most popular modelling languages. Efforts have been made to give security, and in particular access control, a more prominent place in MDE, but most of these approaches require advanced knowledge in security, programming (often declarative), or both, making them difficult to use by less technically trained stakeholders. In this thesis, we propose an approach to modelling, analysing and automatically fixing role-based access control (RBAC) that does not require users to write code or queries themselves. To this end, we use two UML profiles and associated OCL constraints that provide the modelling and analysis features. We propose a taxonomy of OCL constraints and use it to define a partial order between categories of constraints, that we use to propose strategies to speed up the models’ evaluation time. Finally, by representing OCL constraints as constraints on a graph, we propose an automated approach for generating lists of model changes that can be applied to an incorrect model in order to fix it. All these features have been fully integrated into a UML modelling IDE, IBM Rational Software Architect

Model-Based Analysis of Role-Based Access Control

Model-Driven Engineering (MDE) has been extensively studied. Many directions have been explored, sometimes with the dream of providing a fully integrated approach for designers, developers and other stakeholders to create, reason about and modify models representing software systems. Most, but not all, of the research in MDE has focused on general-purpose languages and models, such as Java and UML. Domain-specific and cross-cutting concerns, such as security, are increasingly essential parts of a software system, but are only treated as second-class citizens in the most popular modelling languages. Efforts have been made to give security, and in particular access control, a more prominent place in MDE, but most of these approaches require advanced knowledge in security, programming (often declarative), or both, making them difficult to use by less technically trained stakeholders. In this thesis, we propose an approach to modelling, analysing and automatically fixing role-based access control (RBAC) that does not require users to write code or queries themselves. To this end, we use two UML profiles and associated OCL constraints that provide the modelling and analysis features. We propose a taxonomy of OCL constraints and use it to define a partial order between categories of constraints, that we use to propose strategies to speed up the models’ evaluation time. Finally, by representing OCL constraints as constraints on a graph, we propose an automated approach for generating lists of model changes that can be applied to an incorrect model in order to fix it. All these features have been fully integrated into a UML modelling IDE, IBM Rational Software Architect

Towards security monitoring patterns

Runtime monitoring is performed during system execution to detect whether the system’s behaviour deviates from that described by requirements. To support this activity we have developed a monitoring framework that expresses the requirements to be monitored in event calculus – a formal temporal first order language. Following an investigation of how this framework could be used to monitor security requirements, in this paper we propose patterns for expressing three basic types of such requirements, namely confidentiality, integrity and availability. These patterns aim to ease the task of specifying confidentiality, integrity and availability requirements in monitorable forms by non-expert users. The paper illustrates the use of these patterns using examples of an industrial case study

Reasoning on the usage control security policies over data artifact business process models

The inclusion of security aspects in organizations is a crucial aspect to ensure compliance with both internal and external regulations. Business process models are a well-known mechanism to describe and automate the activities of the organizations, which should include security policies to ensure the correct performance of the daily activities. Frequently, these security policies involve complex data which cannot be represented using the standard Business Process Model Notation (BPMN). In this paper, we propose the enrichment of the BPMN with a UML class diagram to describe the data model, that is also combined with security policies defined using the UCONABC framework annotated within the business process model. The integration of the business process model, the data model, and the security policies provides a context where more complex reasoning can be applied about the satisfiability of the security policies in accordance with the business process and data models. To do so, wetransform the original models, including security policies, into the BAUML framework (an artifact-centric approach to business process modelling). Once this is done, it is possible to ensure that there are no inherent errors in the model (verification) and that it fulfils the business requirements (validation), thus ensuring that the business process and the security policies are compatible and that they are aligned with the business security requirements.This work has been supported by Project PID2020-112540RB-C44 funded by MCIN/AEI/ 10.13039/501100011033, Project TIN2017-87610-R funded by MCIN/AEI/10.13039/501100011033 and FEDER “Una manera de hacer Europa”, Project 2017-SGR-1749 by the Generalitat de Catalunya, Projects COPERNICA (P20 01224) and METAMORFOSIS by the Junta de Andalucía.Peer ReviewedPostprint (published version

Role-Based Access-Control for Databases

Liikudes üha enam paberivaba ari suunas, hoitakse üha enam tundlikku informatsiooni andmebaasides. Sellest tulenevalt on andmebaasid ründajatele väärtuslik sihtmärk. Levinud meetod andmete kaitseks on rollipõhine ligipääsu kontroll (role-based access control), mis piirab süsteemi kasutajate õiguseid vastavalt neile omistatud rollidele. Samas on turvameetmete realiseerimine arendajate jaoks aeganõudev käsitöö, mida teostatakse samaaegselt rakenduse toimeloogika realiseerimisega. Sellest tulenevalt on raskendatud turva vajaduste osas kliendiga läbirääkimine projekti algfaasides. See omakorda suurendab projekti reaalsete arenduskulude kasvamise riski, eriti kui ilmnevad turvalisuse puudujäägid realisatsioonis. Tänapäeva veebirakendustes andmebaasi ühenduste puulimine (connec-tion pooling ), kus kasutatakse üht ja sama ühendust erinevate kasutajate teenindamiseks, rikub vähima vajaliku õiguse printsiipi. Kõikidel ühendunud kasutajatel on ligipääs täpselt samale hulgale andmetele, mille tulemusena võib lekkida tundlik informatsioon (näiteks SQLi süstimine (SQL injection ) või vead rakenduses). Lahenduseks probleemile pakume välja vahendid rollipõhise ligipääsu kontorolli disainimiseks tarkvara projekteerimise faasis. Rollipõhise ligipääsu kontorolli modelleerimiseks kasutame UML'i laiendust SecureUML. Antud mudelist on võimalik antud töö raames valminud vahenditega genereerida koodi, mis kontrollib ligipääsu õiguseid andmebaasi tasemel. Antud madaltasemekontroll vähendab riski, et kasutajad näevad andmeid, millele neil ligipääsu õigused puuduvad. Antud töös läbiviidud uuring näitas, et mudelipõhine turvalisuse arendamise kvaliteet on kõrgem võrreldes programmeerijate poolt kirjutatud koodiga. Kuna turvamudel on loodud projekteerimise faasis on selle semantiline täielikkus ja korrektsus kõrge, millest tulenevalt on seda kerge lugeda ja muuta ning seda on lihtsam kasutada arendajate ja klientide vahelises suhtluses.With the constant march towards a paperless business environment, database systems are increasingly being used to hold more and more sensitive information. This means they present an increasingly valuable target for attackers. A mainstream method for information system security is Role-based Access Control (RBAC), which restricts system access to authorised users. However the implementation of the RBAC policy remains a human intensive activity, typically, performed at the implementation stage of the system development. This makes it difficult to communicate security solutions to the stakeholders earlier and raises the system development cost, especially if security implementation errors are detected. The use of connection pooling in web applications, where all the application users connect to the database via the web server with the same database connection, violates the the principle of minimal privilege. Every connected user has, in principle, access to the same data. This may leave the sensitive data vulnerable to SQL injection attacks or bugs in the application. As a solution we propose the application of the model-driven development to define RBAC mechanism for data access at the design stages of the system development. The RBAC model created using the SecureUML approach is automatically translated to source code, which implements the modelled security rules at the database level. Enforcing access-control at this low level limits the risk of leaking sensitive data to unauthorised users. In out case study we compared SecureUML and the traditional security model, written as a source code, mixed with business logic and user-interface statements. The case study showed that the model-driven security development results in significantly better quality for the security model. Hence the security model created at the design stage contains higher semantic completeness and correctness, it is easier to modify and understand, and it facilitates a better communication of security solutions to the system stakeholders than the security model created at the implementation stage

Developing a domain-specific plug-in for a modelling platform: the good, the bad, the ugly

Domain-Specific Modelling Languages (DSML) allow software engineers to use the techniques and tools of Model-Driven Engineering (MDE) to express, represent and analyse a particular domain. By defining DSMLs as UML profiles, i.e. domain-specific extensions of the UML metamodel, development time for DSMLs can be greatly reduced by extending existing UML tools. In this paper, we reflect on our own experience in building rbacUML, a DSML for Role-Based Access Control modelling and analysis, as a plugin for a UML modelling platform. We describe what motivated our choice, and discuss the advantages and drawbacks of using an existing platform to develop a DSML on top of UML and additional analysis tooling

Towards an incremental development of UML specifications

RapportSpecifying complex systems is a difficult task which cannot be done in one step. Step-by-step development processes have been studied using formal methods, based on refinement mechanisms. The refinement is a key feature for incrementally developing more and more detailed models, preserving correctness in each step. Our purpose is to instantiate this process when using UML/OCL notations. We illustrate it by some development steps of an access control system. At each step, decisions are formalized in terms of different UML notations, making evolve an initial model which expresses the fundamental properties of the system. We show that these properties are preserved by each development step

Modelling, validating, and ranking of secure service compositions

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordIn the world of large-scale applications, software as a service (SaaS) in general and use of microservices, in particular, is bringing service-oriented architectures to a new level: Systems in general and systems that interact with human users (eg, sociotechnical systems) in particular are built by composing microservices that are developed independently and operated by different parties. At the same time, SaaS applications are used more and more widely by enterprises as well as public services for providing critical services, including those processing security or privacy of relevant data. Therefore, providing secure and reliable service compositions is increasingly needed to ensure the success of SaaS solutions. Building such service compositions securely is still an unsolved problem. In this paper, we present a framework for modelling, validating, and ranking secure service compositions that integrate both automated services as well as services that interact with humans. As a unique feature, our approach for ranking services integrates validated properties (eg, based on the result of formally analysing the source code of a service implementation) as well as contractual properties that are part of the service level agreement and, thus, not necessarily ensured on a technical level