A Multiagent Approach to Outbound Intrusion Detection
Mandujano Vergar, Salvador
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A Multiagent Approach to Outbound Intrusion Detection. Ph.D. dissertation by Salvador Mandujano Vergara, Instituto Tecnológico y de Estudios Superiores de Monterrey. Advisor: Prof. Arturo Galván. December � 2004. This is a dissertation on the topic of intrusion detection. It supports the philosophy of system vigilance by exploring the concept of outbound intrusion detection, which is concerned with the identification and collection of evidence that helps prove local resources are being used to compromise external systems. We discuss the motivation behind the approach, explain the need for splitting the scope of intrusion detection into sub-problems, and present trends in computer security that reveal basic design considerations that need to be taken into account when developing modern information security tools. We propose a multiagent architecture for outbound intrusion detection supported by an ontology. Groups of agents collectively monitor outbound network traffic and local activity in order to identify references to neighboring systems that may be indicative of a compromise attempt. We organize agents into sub-environments called agent cells that are connected to each other in a non-hierarchical fashion. Different classes of agents and cells compose the system, which performs attack modeling by employing multiple concurrent agents. Detection cells implement independent misuse intrusion strategies whose output is systematically fed to correlation cells capable of more accurate diagnosis. We present an attack-source-centric ontology that extends previous work in the area. It enables message interpretation and enhanced agent communication within the architecture sim- plifying at the same time system maintenance and facilitating the integration of new components. We describe the implementation of the proposed architecture through the FROID prototype as a proof of concept. This is a misuse-based intrusion detection system built with agent and semantic web open-source technology whose particular focus is the identification of automated remote attack tools. It performs signature generation, matching, and correlation, and supports a signature deployment mechanism over the Internet. We introduce a similarity matching method that improves the performance of existing algorithms by leveraging entropy and frequency properties of the input hereby reducing search time. We link detection with incident response by procuring low false alarm rates that allow us to study local and external reaction methods to outbound intrusion events. We also present a component of the architecture that performs tracing of interactive sessions as a way of identifying the root location of a security event. We describe the experimental design and report the results obtained with the prototype that show the feasibility of the approach as an alternate way of containing the impact of security incidents through the integration of a mesh of monitoring agents.