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A Weakest Precondition Approach to Robustness
KTH, School of Computer Science and Communication (CSC), Theoretical Computer Science, TCS.
2010 (English)In: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 6340, no PART 1, 261-297 p.Article in journal (Refereed) Published
Abstract [en]

With the increasing complexity of information management computer systems, security becomes a real concern. E-government, web-based financial transactions or military and health care information systems are only a few examples where large amount of information can reside on different hosts distributed worldwide. It is clear that any disclosure or corruption of confidential information in these contexts can result fatal. Information flow controls constitute an appealing and promising technology to protect both data confidentiality and data integrity. The certification of the security degree of a program that runs in untrusted environments still remains an open problem in the area of language-based security. Robustness asserts that an active attacker, who can modify program code in some fixed points (holes), is unable to disclose more private information than a passive attacker, who merely observes unclassified data. In this paper, we extend a method recently proposed for checking declassified non-interference in presence of passive attackers only, in order to check robustness by means of weakest precondition semantics. In particular, this semantics simulates the kind of analysis that can be performed by an attacker, i.e., from public output towards private input. The choice of semantics allows us to distinguish between different attacks models and to characterize the security of applications in different scenarios. Our results are sound to address confidentiality and integrity of software running in untrusted environments where different actors can distrust one another. For instance, a web server can be attacked by a third party in order to steal a session cookie or hijack clients to a fake web page.

Place, publisher, year, edition, pages
2010. Vol. 6340, no PART 1, 261-297 p.
Keyword [en]
abstract interpretation, active attackers, declassification, non-interference, program semantics, robustness, security
National Category
Computer Science
URN: urn:nbn:se:kth:diva-81050DOI: 10.1007/978-3-642-17499-5_11ScopusID: 2-s2.0-78650666141OAI: diva2:497084
QC 20120216Available from: 2012-02-10 Created: 2012-02-10 Last updated: 2014-09-08Bibliographically approved
In thesis
1. Logics for Information Flow Security:From Specification to Verification
Open this publication in new window or tab >>Logics for Information Flow Security:From Specification to Verification
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Software is becoming  increasingly  ubiquitous and today we find software running everywhere. There is software driving our favorite  game  application or  inside the web portal we use to read the morning  news, and   when we book a vacation.  Being so commonplace, software has become an easy target to compromise  maliciously or at best to get it wrong. In fact, recent trends and highly-publicized attacks suggest that vulnerable software  is at  the root of many security attacks.     

Information flow security is the research field that studies  methods and techniques to provide strong security guarantees against  software security attacks and vulnerabilities.  The goal of an  information flow analysis is to rigorously check how  sensitive information is used by the software application and ensure that this information does not escape the boundaries of the application, unless it is properly granted permission to do so by the security policy at hand.  This process can   be challenging asit first requires to determine what the applications security policy is and then to provide a mechanism  to enforce that policy against the  software application.  In this thesis  we address the problem of (information flow) policy specification and policy enforcement by leveraging formal methods, in particular logics and language-based analysis and verification techniques.

The thesis contributes to the state of the art of information flow security in several directions, both theoretical and practical. On the policy specification side, we provide a  framework to reason about  information flow security conditions using the notion of knowledge. This is accompanied  by logics that  can be used  to express the security policies precisely in a syntactical manner. Also, we study the interplay between confidentiality and integrity  to enforce security in  presence of active attacks.  On the verification side, we provide several symbolic algorithms to effectively check whether an application adheres to the associated security policy. To achieve this,  we propose techniques  based on symbolic execution and first-order reasoning (SMT solving) to first extract a model of the target application and then verify it against the policy.  On the practical side, we provide  tool support by automating our techniques and  thereby making it possible  to verify programs written in Java or ARM machine code.  Besides the expected limitations, our case studies show that the tools can be used to  verify the security of several realistic scenarios.

More specifically, the thesis consists of two parts and six chapters. We start with an introduction giving an overview of the research problems and the results of the thesis. Then we move to the specification part which  relies on knowledge-based reasoning and epistemic logics to specify state-based and trace-based information flow conditions and on the weakest precondition calculus to certify security in  presence of active attacks.  The second part of the thesis addresses the problem of verification  of the security policies introduced in the first part.  We use symbolic execution  and  SMT solving techniques to enable   model checking of the security properties.  In particular, we implement a tool that verifies noninterference  and declassification policies for Java programs. Finally, we conclude with relational verification of low level code, which is also supported by a tool.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. viii, 127 p.
TRITA-CSC-A, ISSN 1653-5723 ; 2014:13
National Category
Computer Systems
Research subject
Computer Science
urn:nbn:se:kth:diva-150423 (URN)978-91-7595-259-8 (ISBN)
Public defence
2014-10-03, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 14:00 (English)

QC 20140908

Available from: 2014-09-08 Created: 2014-09-03 Last updated: 2014-09-08Bibliographically approved

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