This dissertation presents a series of techniques that help both client devices and network elements defend against a wide variety of worm attacks. These techniques can be deployed to secure emergent networks including peer-to-peer (P2P) file-sharing systems and wireless communication systems.;In recent years, worms have emerged as one of the most disastrous security threats to various information systems and network infrastructures. Although Internet worms have been extensively studied, worm issues in such emergent networks as peer-to-peer (P2P) systems and cellular networks have yet received due attention. This dissertation aims at designing automated, realtime, and systematic countermeasures, which leverage the existing internal communication mechanisms and network infrastructure to contain worm propagation. The proposed defenses consist of security solutions for both client and system software.;For P2P networks, this dissertation first proposes a partition-based scheme and a CDS-based scheme to contain ultra-fast topological worm spreads. These schemes leverage the underlying P2P overlay for distributing automated security patches to vulnerable machines. They are unique in adopting graph-theory techniques for containing fast spreading worms. This dissertation then proposes a P2P-tailored solution to combat file-sharing worms in P2P environments. Our solution consists of a download-based scheme and a search-based scheme. Both schemes utilize the existing file-sharing mechanisms to internally disseminate security patches to participating peers in a timely and distributed fashion.;For cell-phone networks, this dissertation proposes two device-level defenses for securing smartphone software, namely an access-control--based scheme and a GTT-based scheme. These schemes are unique in that they either enforce security policies in phone devices to identify and block worm attacks or leverage artificial intelligence (AI) methods to differentiate human or worm initiators of the phone applications. This dissertation also proposes a systematic countermeasure consisting of both terminal-level and network-level defenses for combating cell-phone worms. Unlike the existing solutions that split the collaboration between the terminal device and the network to throttle system-wide worm spreads, the proposed solution adopts an identity-based signature scheme at both the sender and the receiver side, and a detection-based automated patching scheme at the network side. Combining terminal-level and network-level defenses effectively speeds up the process of worm detection and victim disinfection.;This dissertation also provides solid mathematical analyses, extensive simulations and experiments to evaluate the effectiveness and show the applicability of the proposed defenses. In addition, it discusses some open issues related to the proposed solutions and suggests some interesting directions in combating the worm threats as the emergent networks evolve.
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