University of Hawa1'1 Ubra~Y
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UNIVERSITY OF HAWA1'1 UBRA~Y NETWORK THREAT DETECTION UTILIZING ADAPTIVE AND INNATE IMMUNE SYSTEM METAPHORS A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAW AI 1 IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN COMPUTER SCIENCE MAY 2008 By Robert L. Fanelli Dissertation Committee: Kimberly Binsted, Chairperson Edoardo Biagioni David Chin WesJey Peterson Raymond Panko We certify that we have read this dissertation and that, in our opinion, it is satisfactory in scope and quality as a dissertation for the degree of Doctor of Philosophy in Computer Science. DISSERTATION COMMITTEE ~ ~ Chairperson , i Dedication To Lisa, Anne and John. the true Precious. ii Acknowledgements My thanks go to my advisor, Kim Binsted, for her guidance and support throughout the dissertation process. Thanks also go to my committee members, Edo Biagioni, David Chin, Wes Peterson and Ray Panko for their valuable time, sage advice and keen eyes. I'd like to acknowledge the support of the United States Anny in providing the opportunity to pursue this research. Thanks also go to the International Infonnation Systems Security Certification Consortium, (ISC)2, for their support in the conduct of this research. Finally, heartfelt thanks go to my family for their unwavering support and for putting up with distractedness, irritability, missed weekends and all the other features of life in the computer dungeon. The views expressed in this document are those of the author and do not necessarily reflect the official policy or position of the United States Anny, the Department of Defense or the U.S. Government. iii Abstract This dissertation investigates a hybrid model for network threat detection that combines artificial immune system approaches with conventional intrusion detection methods. The research thesis asserts that a model combining artificial immune system and conventional methods can overcome limitations seen in conventional intrusion detection methods, such as false positive detections and difficulty adapting to novel threats. The Network Threat Recognition with Immune Inspired Anomaly Detection (NetTRIIAD) model presented here incorporates conventional intrusion detection and status monitoring methods as input for an artificial immune system based on the immunological Danger Model. This work details implementation of a prototype NetTRIIAD system and experimentation on a series of intrusion detection scenarios including both known and newly created threats. This dissertation makes several contributions to knowledge in the areas of artificial immune systems and information system security. This work presents a novel methodology for applying artificial immune system techniques to a complex information system security problem. It also presents a working model for integrating artificial immune systems and conventional approaches to network threat detection. A further contribution is to the body of knowledge concerning the relatively new field of Danger Model inspired artificial immune systems and its application to solving complex problems. iv The NetTRIIAD prototype demonstrates a reduction in false positive detections and an improvement in positive predictive value, compared to that of a conventional misuse based intrusion detection system. The prototype also demonstrates the capacity to detect novel threats. These results support the thesis that the hybrid model can overcome some of the limitations of other intrusion detection approaches. This research points to the usefulness of immune-inspired approaches for problems in the domain of information system security, and represents a step toward providing an immune system for self protecting information systems. v Table of Contents Acknowledgements ............................................................................................................ iii Abstract.. ............................................................................................................................ iv List of Tables ..........................................................................................•............•........• xviii List of Figures .................................................................................................................. xix Chapter I Introduction .•.........•............•............................................................................... 1 1.1 Motivation ................................................................................................................. 1 1.2 Research Thesis .....................................................................•......•....••.........•.......•... 3 1.3 Research Goals ...................................••..........•.........•............................................... 3 1.4 Contributions of this Research ...........•............••.......••............................................... 5 1.5 Organization of the Dissertation ............................................................................... 7 Chapter 2 Review of the Literature and Related Work ...................................................... 9 2.1 Introduction ............................................................................................................... 9 2.2 Threat Detection ....................................................................................................... 9 2.2.1 Introduction to Information System Security ......•••.....................•................... 10 2.2.2 Intrusion Detection Systems ....................................................................••...... 11 2.2.3 Intrusion Detection System Models ................................................................. 11 2.2.3.1 Scope ......................................................................................................... 12 2.2.3.2 System Architectures ..................•••........••...........•..................................... 13 2.2.3.3 Misuse Detection ..................................••...........•...................................... 14 2.2.3.4 Anomaly Detection .....................•.........•................................................... 15 2.2.4 Intrusion Detection System Background ......................................................... 18 vi 2.3 The Natural Immune System .................................................................................. 20 2.3.1 The Innate and Adaptive Immune Systems ..................................................... 21 2.3.2 Receptors, Antigens, and Antibodies ............................................................... 23 2.3.3 Self - NonselfDiscrimination ......................................................................... 25 2.3.4 Immune System Components .......................................................................... 25 2.3.4.1 Lymphatic Cells ........................................................................................ 26 2.3.4.2 Antigen Presenting Cells........................................................................... 27 2.3.5 Immune Reactions ........................................................................................... 28 2.3.5.1 T Cell Development and Selection ........................................................... 28 2.3.5.2 T Cell Activation ....................................................................................... 30 2.3.5.3 B Cell Development .................................................................................. 31 2.3.5.4 B Cell Activation ...................................................................................... 31 2.3.5.5 Affinity Maturation ................................................................................... 32 2.3.5 Immune Memol)', Primal)' and Secondal)' Response ...................................... 34 2.3.6 The Danger Model ........................................................................................... 35 2.3.7 Computational Characteristics of the Natural Immune System ....................... 38 2.3.7.1 Pattern Recognition Capability .•............................................................... 38 2.3.7.2 Learning Capability .................................................................................. 39 2.3.7.3 Information Storage Capability.............•................................................... 39 2.3.7.4 Comparison to the Nervous System .......................................................... 40 2.3.8 Conclusion ....................................................................................................... 40 2.4 Artificial Immune Systems ..................................................................................... 41 vii 2.4.1 Artificial Immune System Introduction ........................................................... 41 2.4.1.1 Useful Features Gained from the Immune inspiration ............................. 42 2.4.1.2 The Origins of Artificial Immune Systems ............................................... 43 2.4.1.3 Elements of Artificial Immune Systems ................................................... 44 2.4.2 Artificial Immune System Representation Methods ........................................ 45 2.4.2.1 Antigens and Antibodies .....•..........••........••.....................•......................... 45 2.4.2.2 The Self - NonselfModel .•.................................•..•.................................. 46 2.4.2.3 Shape Spaces ...........................................................................................