Securing Systems Applied Security Architecture and Threat Models

416 Pages·2015·14.482 MB·English

by  Brook S. E. Schoenfield

Securing
Systems
Applied Security
Architecture and
Threat Models

Securing
Systems
Applied Security
Architecture and
Threat Models
Brook S.E. Schoenfield
Forewords by John N. Stewart and James F. Ransome
CRC Press
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Version Date: 20150417
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Dedication
To the many teachers who’ve pointed me down the path; the managers who have sup-
ported my explorations; the many architects and delivery teams who’ve helped to refine
the work; to my first design mentors—John Caron, Roddy Erickson, and Dr. Andrew
Kerne—without whom I would still have no clue; and, lastly, to Hans Kolbe, who once
upon a time was our human fuzzer.
Each of you deserves credit for whatever value may lie herein.
The errors are all mine.
v

Contents
Dedication v
Contents vii
Foreword by John N. Stewart xiii
Foreword by Dr. James F. Ransome xv
Preface xix
Acknowledgments xxv
About the Author xxvii
Part I
Introduction 3
The Lay of Information Security Land 3
The Structure of the Book 7
References 8
Chapter 1: Introduction 9
1.1 Breach! Fix It! 11
1.2 Information Security, as Applied to Systems 14
1.3 Applying Security to Any System 21
References 25
Chapter 2: The Art of Security Assessment 27
2.1 Why Art and Not Engineering? 28
2.2 Introducing “The Process” 29
vii
viii Securing Systems
2.3 Necessary Ingredients 33
2.4 The Threat Landscape 35
2.4.1 Who Are These Attackers? Why Do They Want
to Attack My System? 36
2.5 How Much Risk to Tolerate? 44
2.6 Getting Started 51
References 52
Chapter 3: Security Architecture of Systems 53
3.1 Why Is Enterprise Architecture Important? 54
3.2 The “Security” in “Architecture” 57
3.3 Diagramming For Security Analysis 59
3.4 Seeing and Applying Patterns 70
3.5 System Architecture Diagrams and Protocol Interchange
Flows (Data Flow Diagrams) 73
3.5.1 Security Touches All Domains 77
3.5.2 Component Views 78
3.6 What’s Important? 79
3.6.1 What Is “Architecturally Interesting”? 79
3.7 Understanding the Architecture of a System 81
3.7.1 Size Really Does Matter 81
3.8 Applying Principles and Patterns to Specific Designs 84
3.8.1 Principles, But Not Solely Principles 96
Summary 98
References 98
Chapter 4: Information Security Risk 101
4.1 Rating with Incomplete Information 101
4.2 Gut Feeling and Mental Arithmetic 102
4.3 Real-World Calculation 105
4.4 Personal Security Posture 106
4.5 Just Because It Might Be Bad, Is It? 107
4.6 The Components of Risk 108
4.6.1 Threat 110
4.6.2 Exposure 112
4.6.3 Vulnerability 117
4.6.4 Impact 121
4.7 Business Impact 122
4.7.1 Data Sensitivity Scales 125
Contents ix
4.8 Risk Audiences 126
4.8.1 The Risk Owner 127
4.8.2 Desired Security Posture 129
4.9 Summary 129
References 130
Chapter 5: Prepare for Assessment 133
5.1 Process Review 133
5.1.1 Credible Attack Vectors 134
5.1.2 Applying ATASM 135
5.2 Architecture and Artifacts 137
5.2.1 Understand the Logical and Component Architecture
of the System 138
5.2.2 Understand Every Communication Flow and Any
Valuable Data Wherever Stored 140
5.3 Threat Enumeration 145
5.3.1 List All the Possible Threat Agents for This Type
of System 146
5.3.2 List the Typical Attack Methods of the Threat Agents 150
5.3.3 List the System-Level Objectives of Threat Agents
Using Their Attack Methods 151
5.4 Attack Surfaces 153
5.4.1 Decompose (factor) the Architecture to a Level That
Exposes Every Possible Attack Surface 154
5.4.2 Filter Out Threat Agents Who Have No Attack
Surfaces Exposed to Their Typical Methods 159
5.4.3 List All Existing Security Controls for Each Attack
Surface 160
5.4.4 Filter Out All Attack Surfaces for Which There Is
Sufficient Existing Protection 161
5.5 Data Sensitivity 163
5.6 A Few Additional Thoughts on Risk 164
5.7 Possible Controls 165
5.7.1 Apply New Security Controls to the Set of Attack
Services for Which There Isn’t Sufficient Mitigation 166
5.7.2 Build a Defense-in-Depth 168
5.8 Summary 170
References 171
Part I
Summary 173