79 research outputs found
Possibilistic Information Flow Control for Workflow Management Systems
In workflows and business processes, there are often security requirements on
both the data, i.e. confidentiality and integrity, and the process, e.g.
separation of duty. Graphical notations exist for specifying both workflows and
associated security requirements. We present an approach for formally verifying
that a workflow satisfies such security requirements. For this purpose, we
define the semantics of a workflow as a state-event system and formalise
security properties in a trace-based way, i.e. on an abstract level without
depending on details of enforcement mechanisms such as Role-Based Access
Control (RBAC). This formal model then allows us to build upon well-known
verification techniques for information flow control. We describe how a
compositional verification methodology for possibilistic information flow can
be adapted to verify that a specification of a distributed workflow management
system satisfies security requirements on both data and processes.Comment: In Proceedings GraMSec 2014, arXiv:1404.163
An Automata Based Approach for Verifying Information Flow Properties
AbstractWe present an automated verification technique to verify trace based information flow properties for finite state systems. We show that the Basic Security Predicates (BSPs) defined by Mantel in [Mantel, H., Possibilistic Definitions of Security – An Assembly Kit, in: Proceedings of the 13th IEEE Computer Security Foundations Workshop (2000), pp. 185–199], which are shown to be the building blocks of known trace based information flow properties, can be characterised in terms of regularity preserving language theoretic operations. This leads to a decision procedure for checking whether a finite state system satisfies a given BSP. Verification techniques in the literature (e.g. unwinding) are based on the structure of the transition system and are incomplete in some cases. In contrast, our technique is language based and complete for all information flow properties that can be expressed in terms of BSPs
Composition and Declassification in Possibilistic Information Flow Security
Formal methods for security can rule out whole classes of security vulnerabilities, but applying them in practice remains challenging. This thesis develops formal verification techniques for information flow security that combine the expressivity and scalability strengths of existing frameworks. It builds upon Bounded Deducibility (BD) Security, which allows specifying and verifying fine-grained policies about what information may flow when to whom. Our main technical result is a compositionality theorem for BD Security, providing scalability by allowing us to verify security properties of a large system by verifying smaller components. Its practical utility is illustrated by a case study of verifying confidentiality properties of a distributed social media platform. Moreover, we discuss its use for the modular development of secure workflow systems, and for the security-preserving enforcement of safety and security properties other than information flow control
Enforcing Information Flow Security Properties in Cyber-Physical Systems: A Generalized Framework Based on Compensation
This paper presents a general theory of event compensation as an information flow security enforcement mechanism for Cyber-Physical Systems (CPSs). The fundamental research problem being investigated is that externally observable events in modern CPSs have the propensity to divulge sensitive settings to adversaries, resulting in a confidentiality violation. This is a less studied yet emerging concern in modern system security. A viable method to mitigate such violations is to use information flow security based enforcement mechanisms since access control based security models cannot impose restrictions on information propagation. Further, the disjoint nature of security analysis is not appropriate for systems with highly integrated physical and cyber infrastructures. The proposed compensation based security framework is foundational work that unifies cyber and physical aspects of security through the shared semantics of information flow. A DC circuit example is presented to demonstrate this concept
A Verified Information-Flow Architecture
SAFE is a clean-slate design for a highly secure computer system, with
pervasive mechanisms for tracking and limiting information flows. At the lowest
level, the SAFE hardware supports fine-grained programmable tags, with
efficient and flexible propagation and combination of tags as instructions are
executed. The operating system virtualizes these generic facilities to present
an information-flow abstract machine that allows user programs to label
sensitive data with rich confidentiality policies. We present a formal,
machine-checked model of the key hardware and software mechanisms used to
dynamically control information flow in SAFE and an end-to-end proof of
noninterference for this model.
We use a refinement proof methodology to propagate the noninterference
property of the abstract machine down to the concrete machine level. We use an
intermediate layer in the refinement chain that factors out the details of the
information-flow control policy and devise a code generator for compiling such
information-flow policies into low-level monitor code. Finally, we verify the
correctness of this generator using a dedicated Hoare logic that abstracts from
low-level machine instructions into a reusable set of verified structured code
generators
Formalizing probabilistic noninterference
We present an Isabelle formalization of probabilistic noninterference for a multi-threaded language with uniform scheduling. Unlike in previous settings from the literature, here probabilistic behavior comes from both the scheduler and the individual threads, making the language more realistic and the mathematics more challenging. We study resumption-based and trace-based notions of probabilistic noninterference and their relationship, and also discuss compositionality w.r.t. the language constructs and type-system-like syntactic criteria. The
formalization uses recent development in the Isabelle probability theory library
Model-driven Information Flow Security for Component-Based Systems
International audienceThis paper proposes a formal framework for studying information flow security in component-based systems. The security policy is defined and verified from the early steps of the system design. Two kinds of non-interference properties are formally introduced and for both of them, sufficient conditions that ensures and simplifies the automated verification are proposed. The verification is compositional, first locally, by checking the behavior of every atomic component and then globally, by checking the inter-components communication and coordination. The potential benefits are illustrated on a concrete case study about constructing secure heterogeneous distributed systems
Unwinding in Information Flow Security
We study information flow security properties which are persistent, in the sense that if a system is secure then all of its reachable states are secure too. We present a uniform characterization of these properties in terms of a general unwinding schema. This unwinding characterization allows us to prove several compositionality properties of the considered security classes. Moreover, we exploit the unwinding condition to dictate the form of the rules we can use to incrementally develop secure processes and to rectify insecure processes
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