Conceptual Model for Communication

A variety of idealized models of communication systems exist, and all may have something in common. Starting with Shannons communication model and ending with the OSI model, this paper presents progressively more advanced forms of modeling of communication systems by tying communication models together based on the notion of flow. The basic communication process is divided into different spheres (sources, channels, and destinations), each with its own five interior stages, receiving, processing, creating, releasing, and transferring of information. The flow of information is ontologically distinguished from the flow of physical signals, accordingly, Shannons model, network based OSI models, and TCP IP are redesigned.Comment: 13 pages IEEE format, International Journal of Computer Science and Information Security, IJCSIS November 2009, ISSN 1947 5500, http://sites.google.com/site/ijcsis

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

FORTES: Forensic Information Flow Analysis of Business Processes

Nearly 70% of all business processes in use today rely on automated workflow systems for their execution. Despite the growing expenses in the design of advanced tools for secure and compliant deployment of workflows, an exponential growth of dependability incidents persists. Concepts beyond access control focusing on information flow control offer new paradigms to design security mechanisms for reliable and secure IT-based workflows. This talk presents FORTES, an approach for the forensic analysis of information flow properties. FORTES claims that information flow control can be made usable as a core of an audit-control system. For this purpose, it reconstructs workflow models from secure log files (i.e. execution traces) and, applying security policies, analyzes the information flows to distinguish security relevant from security irrelevant information flows. FORTES thus cannot prevent security policy violations, but by detecting them with well-founded analysis, improve the precision of audit controls and the generated certificates

Verifying Data Secure Flow in AUTOSAR Models by Static Analysis

This paper presents a method to check data secure flow in security annotated AUTOSAR models. The approach is based on information flow analysis and abstract interpretation. The analysis computes the lowest security level of data sent on a communication, according to the annotations in the model and the code of runnables. An abstract interpreter executes runnables on abstract domains that abstract from real values and consider only data dependency levels. Data secure flow is verified if data sent on a communication always satisfy the security annotation in the model. The work has been developed in the EU project Safure, where modeling extensions to AUTOSAR have been proposed to improve security in automotive communications

Security Property Violation in CPS Through Timing

Security in a cyber-physical system (CPS) is not well understood. Interactions between components in the cyber and physical domains lead to unintended information flow. This paper makes use of formal information flow models to describe leakage in a model CPS, the Cooperating FACTS Power System. Results show that while a casual observer cannot ascertain confidential internal information, when application semantics, including timing, are considered, this confidentiality is lost. Model checking is used to verify the result. The significance of the paper is in showing an example of the complex interactions that occur between the Cyber and Physical domains and their impact on security

Refactoring preserves security

Refactoring allows changing a program without changing its behaviour from an observer’s point of view. To what extent does this invariant of behaviour also preserve security? We show that a program remains secure under refactoring. As a foundation, we use the Decentralized Label Model (DLM) for specifying secure information flows of programs and transition system models for their observable behaviour. On this basis, we provide a bisimulation based formal definition of refactoring and show its correspondence to the formal notion of information flow security (noninterference). This permits us to show security of refactoring patterns that have already been practically explored

CEEME: compensating events based execution monitoring enforcement for Cyber-Physical Systems

Fundamentally, inherently observable events in Cyber-Physical Systems with tight coupling between cyber and physical components can result in a confidentiality violation. By observing how the physical elements react to cyber commands, adversaries can identify critical links in the system and force the cyber control algorithm to make erroneous decisions. Thus, there is a propensity for a breach in confidentiality leading to further attacks on availability or integrity. Due to the highly integrated nature of Cyber-Physical Systems, it is also extremely difficult to map the system semantics into a security framework under existing security models. The far-reaching objective of this research is to develop a science of selfobfuscating systems based on the composition of simple building blocks. A model of Nondeducibility composes the building blocks under Information Flow Security Properties. To this end, this work presents fundamental theories on external observability for basic regular networks and the novel concept of event compensation that can enforce Information Flow Security Properties at runtime --Abstract, page iii

Refactoring preserves security

Refactoring allows changing a program without changing its behaviour from an observer’s point of view. To what extent does this invariant of behaviour also preserve security? We show that a program remains secure under refactoring. As a foundation, we use the Decentralized Label Model (DLM) for specifying secure information flows of programs and transition system models for their observable behaviour. On this basis, we provide a bisimulation based formal definition of refactoring and show its correspondence to the formal notion of information flow security (noninterference). This permits us to show security of refactoring patterns that have already been practically explored

Cyber physical security of avionic systems

“Cyber-physical security is a significant concern for critical infrastructures. The exponential growth of cyber-physical systems (CPSs) and the strong inter-dependency between the cyber and physical components introduces integrity issues such as vulnerability to injecting malicious data and projecting fake sensor measurements. Traditional security models partition the CPS from a security perspective into just two domains: high and low. However, this absolute partition is not adequate to address the challenges in the current CPSs as they are composed of multiple overlapping partitions. Information flow properties are one of the significant classes of cyber-physical security methods that model how inputs of a system affect its outputs across the security partition. Information flow supports traceability that helps in detecting vulnerabilities and anomalous sources, as well as helps in rendering mitigation measures. To address the challenges associated with securing CPSs, two novel approaches are introduced by representing a CPS in terms of a graph structure. The first approach is an automated graph-based information flow model introduced to identify information flow paths in the avionics system and partition them into security domains. This approach is applied to selected aspects of the avionic systems to identify the vulnerabilities in case of a system failure or an attack and provide possible mitigation measures. The second approach is based on graph neural networks (GNN) to classify the graphs into different security domains. Using these two approaches, successful partitioning of the CPS into different security domains is possible in addition to identifying their optimal coverage. These approaches enable designers and engineers to ensure the integrity of the CPS. The engineers and operators can use this process during design-time and in real-time to identify failures or attacks on the system”--Abstract, page iii

Unwinding biological systems

Unwinding conditions have been fruitfully exploited in Information Flow Security to define persistent security properties. In this paper we investigate their meaning and possible uses in the analysis of biological systems. In particular, we elaborate on the notion of robustness and propose some instances of unwinding over the process algebra Bio-PEPA and over hybrid automata. We exploit such instances to analyse two case-studies: Neurospora crassa circadian system and Influenza kinetics models