Modeling and justification of the store and forward protocol: Covert channel analysis

Hind Al Falasi, Liren Zhang

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    In an environment where two networks with different security levels are allowed to communicate, a covert channel is created. The paper aims at calculating the probability of establishing a covert channel between the high security network and the low security network using Markov Chain Model. The communication between the networks follows the Bell-LaPadula (BLP) security model. The BLP model is a "No read up, No write down" model where up indicates an entity with a high security level and down indicates an entity with a low security level. In networking, the only way to enforce the BLP model is to divide a network into separate entities, networks with a low security level, and others with a high security level. This paper discusses our analysis of the Store and Forward Protocol that enforces the BLP security model. The Store and Forward Protocol (SAFP) is a gateway that forwards all data from a low security network to a high security network, and it sends acknowledgments to the low security network as if they were sent from the high security network; thereby achieving reliability of the communication in this secure environment. A timing covert channel can be established between the two networks by using the times of the acknowledgments to signal a message from the high security network to the low security network. A high security network may send acknowledgments immediately or with some delay where the time of the acknowledgments arrival is used to convey the message. The covert channel probability is found to be equal to the blocking probability of the SAFP buffer when analyzing the problem using Markov Chain Model. Increasing the size of the buffer at the SAFP decreases the covert channel probability. Carefully determining the size of the buffer of the SAFP ensures minimizing the covert channel probability.

    Original languageEnglish
    Title of host publication6th International Conference on Information Warfare and Security, ICIW 2011
    PublisherCurran Associates Inc.
    Pages8-13
    Number of pages6
    ISBN (Print)9781622766758
    Publication statusPublished - 2011
    Event6th International Conference on Information Warfare and Security, ICIW 2011 - Washington, DC, United States
    Duration: Mar 17 2011Mar 18 2011

    Publication series

    Name6th International Conference on Information Warfare and Security, ICIW 2011

    Other

    Other6th International Conference on Information Warfare and Security, ICIW 2011
    Country/TerritoryUnited States
    CityWashington, DC
    Period3/17/113/18/11

    Keywords

    • Access model
    • Covert channel
    • Markov chain model
    • Store and forward protocol

    ASJC Scopus subject areas

    • Information Systems
    • Safety, Risk, Reliability and Quality

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