Browsing by Author "Schuchard, Max"

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    Adversarial Degradation of the Availability of Routing Infrastructures and Other Internet-Scale Distributed Systems
    (2016-06) Schuchard, Max
    The Internet relies on its routing infrastructure, a globally spanning distributed system of special purpose computers call routers, to deliver packets between hosts. In order to build the paths data will travel, routers execute a routing protocol called the Border Gateway Protocol, or BGP. BGP is built to be decentralized and highly accommodating to arbitrary preferences of the organizations that own routers. This dissertation focuses on examining the following thesis statement. The current state of BGP, coupled with the Internet's extreme level of topological complexity, allows adversaries who can interact with BGP routers to degrade the availability properties of both the entire Internet routing infrastructure and other Internet-scale distributed systems. The research in this work breaks down into two independent arcs. The first arc focuses on attacks which aim to disrupt the availability of large portions on the Internet's routing infrastructure. Through both simulation and experimentation with representative devices, this work demonstrates that a variety of adversaries can prevent large portions of the Internet from being able to correctly build paths to end destinations. The second arc focuses on how those who control routers, and therefore can decide how the routers will select paths, can attack the availability of distributed systems which closely interact with the transit infrastructure of the Internet. Specifically the work shows how, by altering the BGP decision making process slightly, a variety of systems, ranging from censorship circumvention tools to surveillance systems, can be defeated by such an adversary without loss of general connectivity.
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    Taking Routers Off Their Meds: Unstable Routers and the Buggy BGP Implementations That Cause Them
    (2011-11-30) Schuchard, Max; Thompson, Christopher; Hopper, Nicholas J.; Kim, Yongdae
    Both academic research and historical incidents have shown the impact of unstable BGP speakers on network performance and reliability. A large amount of time and energy has been invested improving router stability. In this paper, we show how an adversary in control of a BGP speaker in a transit AS can cause a victim router in an arbitrary location on the Internet to become unstable. Through experimentation with both hardware and software routers, we examine the behavior of routers under abnormal conditions and come to four conclusions. First, routers placed in certain states behave in anything but a stable manner. Second, unexpected but perfectly legal BGP messages can place routers into those states with disconcerting ease. Third, an adversary can use these messages to disrupt a victim router to which he is not directly connected. Fourth, modern best practices do little to prevent these attacks. These conclusions lead us to recommend more rigorous testing of BGP implementations, focusing as much on protocol correctness as software correctness.