Browsing by Author "Anwar, Mohd"

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    An Access Control Model for Facebook-Style Social Network Systems
    (2010-07-02T20:08:24Z) Anwar, Mohd; Zhao, Zhen; Fong, Philip W.L.
    Recent years have seen unprecedented growth in the popularity of social network systems, with Facebook being an archetypical example. The access control paradigm behind the privacy preservation mechanism of Facebook is distinctly different from such existing access control paradigms as Discretionary Access Control, Role-Based Access Control, Capability Systems, and TrustManagement Systems. This work takes a first step in deepening the understanding of this access control paradigm, by proposing an access control model that formalizes and generalizes the access control mechanism of Facebook. The model can be instantiated into a family of Facebook-style social network systems, each with a recognizably different access control mechanism, so that Facebook is but one instantiation of the model. We also demonstrate that the model can be instantiated to express policies that are not currently supported by Facebook, and yet these policies possess rich and natural social significance. Among these policies, we formally identify and characterize a special family of policies known as relational policies, which base their authorization decisions on the dynamic relationship between the resource owner and accessor. We believe the family of relational policies is a unique feature of social network systems. An executable encoding of this model has been developed to support experimentation with various instantiation of our access control model. This work thus delineates the design space of access control mechanisms for Facebook-style social network systems, and lays out a formal framework for policy analysis in these systems.
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    ItemOpen Access
    Access Control Policy Analysis with a Visualization Tool for Social Network Systems
    (2011-03-17T16:27:12Z) Fong, Philip; Anwar, Mohd
    Understanding privacy implications of access control policies is a complex task for the users of social network systems. Users need tool support to articulate on access scenarios and perform policy analysis. In this work, we develop a prototypical tool for reflective policy assessment (RPA) – a process in which a user examines her profile from the viewpoint of another user in her extended neighborhood in the social graph. Since an unrestricted view of one's extended neighborhood may compromise the privacy of others, our visualization tool approximates the extended neighborhood of a user in such a way that policy assessment can still be conducted in a meaningful manner, while the privacy of other users is preserved. We verify the utility and usability of our tool in a within-subject user study.
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    Inference Attacks by Third-Party Extensions to Social Network Systems
    (2010-11-01T18:13:14Z) Ahmadinejad, Seyed Hossein; Anwar, Mohd; Fong, Philip
    We study inference attacks that can be launched via the extension API of Facebook. We explain the threat of these attacks through a reduction to authentication attacks, devise a taxonomy for such attacks, and propose a risk metric to help subscribers of third-party applications refine their privacy expectations.
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    A Privacy Preservation Model for Facebook-Style Social Network Systems
    (2009-04-29T17:18:39Z) Fong, Philip; Anwar, Mohd; Zhao, Zhen
    Recent years have seen unprecedented growth in the popularity of social network systems, with Facebook being an archetypical example. The access control paradigm behind the privacy preservation mechanism of Facebook is distinctly different from such existing access control paradigms as Discretionary Access Control, Role-Based Access Control, Capability Systems, and Trust Management Systems. This work takes a first step in deepening the understanding of this access control paradigm, by proposing an access control model that formalizes and generalizes the privacy preservation mechanism of Facebook. The model can be instantiated into a family of Facebook-style social network systems, each with a recognizably different access control mechanism, so that Facebook is but one instantiation of the model. We also demonstrate that the model can be instantiated to express policies that are not currently supported by Facebook but possess rich and natural social significance. This work thus delineates the design space of privacy preservation mechanisms for Facebook-style social network systems, and lays out a formal framework for policy analysis in these systems.
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    ItemOpen Access
    Visualizing Privacy Implications of Access Control Policies in Social Network Systems
    (2009-05-08T16:08:00Z) Anwar, Mohd; Fong, Philip; Yang, Xue-Dong; Hamilton, Howard
    We hypothesize that, in a Facebook-style social network system, proper visualization of one’s extended neighborhood could help the user understand the privacy implications of her access control policies. However, an unrestricted view of one’s extended neighborhood may compromise the privacy of others. To address this dilemma, we propose a privacy-enhanced visualization tool, which approximates the extended neighborhood of a user in such a way that policy assessment can still be conducted in a meaningful manner, while the privacy of other users is preserved.