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John R. Vacca Network and System Security This page intentionally left blank Network and System Security Editor John R. Vacca AMSTERDAM • BOSTON • HEIDELBERG • LONDON NEW YORK • OXFORD • PARIS • SAN DIEGO SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Syngress is an imprint of Elsevier Syngress is an imprint of Elsevier 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA The Boulevard, Langford Lane, Kidlington, Oxford, OX5 1GB, UK Network and System Security # 2010 Elsevier Inc. All rights reserved. Material in the work originally appeared in the Computer and Information Security Handbook, edited by John R. Vacca (Elsevier, Inc. 2009). No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data Vacca, John R. Network and system security / by John R. Vacca. p. cm. Includes bibliographical references and index. ISBN 978-1-59749-535-6 (alk. paper) 1. Computer networks—Security measures. I. Title. TK5105.59.V34 2010 005.8—dc22 2009052077 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. ISBN: 978-1-59749-535-6 Printed in the United States of America 1011121310987654321 Elsevier Inc., the author(s), and any person or firm involved in the writing, editing, or production (collectively “Makers”) of this book (“the Work”) do not guarantee or warrant the results to be obtained from the Work. For information on rights, translations, and bulk sales, contact Matt Pedersen, Commercial Sales Director and Rights; email [email protected] For information on all Syngress publications visit our Web site at www.syngress.com This book is dedicated to my wife Bee v This page intentionally left blank Contents Foreword ........................................................................................................XV Acknowledgments ..........................................................................................XVII About the Editor ............................................................................................XIX List of Contributors ........................................................................................XXI Introduction .................................................................................................XXIII Chapter 1: Building a Secure Organization.......................................................... 1 1. Obstacles to Security............................................................................................... 1 Security Is Inconvenient.............................................................................................2 Computers Are Powerful and Complex ....................................................................2 Computer Users Are Unsophisticated........................................................................2 Computers Created Without a Thought to Security .................................................3 Current Trend Is to Share, Not Protect .....................................................................3 Data Accessible from Anywhere ...............................................................................4 Security Isn’t About Hardware and Software ...........................................................4 The Bad Guys Are Very Sophisticated .....................................................................5 Management Sees Security as a Drain on the Bottom Line ....................................5 2. Ten Steps to Building a Secure Organization........................................................ 6 A. Evaluate the Risks and Threats ............................................................................7 B. Beware of Common Misconceptions....................................................................9 C. Provide Security Training for IT Staff—Now and Forever ..............................11 D. Think “Outside the Box” ....................................................................................13 E. Train Employees: Develop a Culture of Security..............................................17 F. Identify and Utilize Built-In Security Features of the Operating System and Applications.....................................................................................18 G. Monitor Systems..................................................................................................22 H. Hire a Third Party to Audit Security..................................................................25 I. Don’t Forget the Basics ......................................................................................26 J. Patch, Patch, Patch ..............................................................................................28 vii viii Contents Chapter 2: A Cryptography Primer................................................................... 33 1. What Is Cryptography? What Is Encryption? ...................................................... 34 How Is Cryptography Done? ...................................................................................34 2. Famous Cryptographic Devices ............................................................................ 35 The Lorenz Cipher ...................................................................................................35 Enigma......................................................................................................................36 3. Ciphers ................................................................................................................... 37 The Substitution Cipher ...........................................................................................37 The Shift Cipher.......................................................................................................38 The Polyalphabetic Cipher.......................................................................................44 The Kasiski/Kerckhoff Method................................................................................46 4. Modern Cryptography ........................................................................................... 47 The Vernam Cipher (Stream Cipher) ......................................................................47 The One-Time Pad ...................................................................................................48 Cracking Ciphers......................................................................................................49 Some Statistical Tests for Cryptographic Applications by Adrian Fleissig...........50 The XOR Cipher and Logical Operands.................................................................51 Block Ciphers ...........................................................................................................53 5. The Computer Age................................................................................................ 54 Data Encryption Standard ........................................................................................55 Theory of Operation.................................................................................................55 Implementation .........................................................................................................56 Rivest, Shamir, and Adleman (RSA) ......................................................................57 Advanced Encryption Standard (AES or Rijndael) ................................................57 Chapter 3: Preventing System Intrusions ........................................................... 59 1. So, What Is an Intrusion? ................................................................................... 60 2. Sobering Numbers ............................................................................................... 60 3. Know Your Enemy: Hackers versus Crackers................................................... 61 4. Motives ................................................................................................................ 63 5. Tools of the
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