Holistic confidentiality in open networks [Elektronische Ressource] / vorgelegt von Kyriakos Alexis Pimenidis

Lexi Pimenidis

Sujets

• Informatik

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2009
• Nombre de lectures: 18
• Langue: English

Extrait

Holistic Confidentiality in
Open Networks
Von der Fakultät für Mathematik, Informatik und
Naturwissenschaften der RWTH Aachen University zur
Erlangung des akademischen Grades eines Doktors der
Naturwissenschaften genehmigte Dissertation
vorgelegt von
Diplom-Informatiker Kyriakos Alexis Pimenidis
aus Münster, Deutschland
Berichter: Universitätsprofessor Dr. rer. nat. Dr. h.c. Otto Spaniol
Universitätsprofessor Dr. rer. nat. Dogan Kesdogan
Tag der mündlichen Prüfung: 10. Februar 2009
Diese Dissertation ist auf den Internetseiten der
Hochschulbibliothek online verfügbar.This work was created with the help and support of many helpful and kind people.
Representative for all, I’d like to thank my wife for her endless patience.
Thank you.Contents
Contents i
List of Figures v
List of Tables vii
1 Introduction 1
1.1 Anonymous Communication . . . . . . . . . . . . . . . . . . . . 2
1.2 Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.1 Roadmap, Constructive Part . . . . . . . . . . . . . . . . 4
1.2.2 Roadmap: Devil’s Advocate . . . . . . . . . . . . . . . . 5
2 Terminology and Scenario 9
2.1 Computer Networks . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.1 The Internet Protocol . . . . . . . . . . . . . . . . . . . . 10
2.1.2 Overlay Networks . . . . . . . . . . . . . . . . . . . . . 13
2.2 IT Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.1 Host Security . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.2 Network Security . . . . . . . . . . . . . . . . . . . . . . 19
2.2.3 Cryptography . . . . . . . . . . . . . . . . . . . . . . . . 21
2.2.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2.5 Attack Trees . . . . . . . . . . . . . . . . . . . . . . . . 24
2.3 Anonymity-Related Terminology . . . . . . . . . . . . . . . . . . 26
2.4 Setup, Scenario and Setting . . . . . . . . . . . . . . . . . . . . . 29
2.4.1 Node Operators . . . . . . . . . . . . . . . . . . . . . . . 31
2.4.2 Internet Service Providers . . . . . . . . . . . . . . . . . 31
2.4.3 Users . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.4.4 Service Providers . . . . . . . . . . . . . . . . . . . . . . 37
2.4.5 Law Enforcement, Crime Prosecution . . . . . . . . . . . 37
2.4.6 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
iii CONTENTS
3 Anonymizing Networks 41
3.1 Theoretical Models . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.1.1 Broadcast . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.1.2 Layered Encryption, Mixing, Onion Routing . . . . . . . 43
3.1.3 DC-networks . . . . . . . . . . . . . . . . . . . . . . . . 44
3.1.4 Other methods . . . . . . . . . . . . . . . . . . . . . . . 45
3.2 Deployed Systems . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.2.1 Basic Techniques . . . . . . . . . . . . . . . . . . . . . . 47
3.2.2 Tor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.2.3 AN.ON, also known as JAP or Jondos . . . . . . . . . . . 51
3.2.4 Invisible Internet Project, I2P . . . . . . . . . . . . . . . 51
3.2.5 Mixmaster and Mixminion . . . . . . . . . . . . . . . . . 52
3.2.6 Minor Projects . . . . . . . . . . . . . . . . . . . . . . . 53
3.2.7 Abandoned Implementations . . . . . . . . . . . . . . . . 55
3.2.8 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4 Value-Added Works 61
4.1 Server-Side Enforced Anonymity . . . . . . . . . . . . . . . . . . 61
4.2 Virtual Anonymous Networks . . . . . . . . . . . . . . . . . . . 63
4.3 Quality of Service . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
5 Attackers 71
5.1 Theoretical Attacker Models . . . . . . . . . . . . . . . . . . . . 73
5.1.1 Simple Attacker Models . . . . . . . . . . . . . . . . . . 73
5.1.2 Simple Taxonomies . . . . . . . . . . . . . . . . . . . . . 73
5.1.3 Taxonomies . . . . . . . . . . . . . . . . . . . . . . . . . 74
5.1.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.2 Practical Attacker Model . . . . . . . . . . . . . . . . . . . . . . 76
5.2.1 Properties of an Attacker . . . . . . . . . . . . . . . . . . 77
5.2.2 Attackers’ Intentions and Motivations . . . . . . . . . . . 81
5.2.3 Classification . . . . . . . . . . . . . . . . . . . . . . . . 83
5.2.4 Evaluation of the Attacker Model . . . . . . . . . . . . . 87
5.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88CONTENTS iii
6 Attacks on Anonymizing Networks 91
6.1 Flow of an anonymized message . . . . . . . . . . . . . . . . . . 92
6.2 Attacks on Hardware . . . . . . . . . . . . . . . . . . . . . . . . 95
6.2.1 Attacks . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.2.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 96
6.3 Attacks on Operating Systems . . . . . . . . . . . . . . . . . . . 97
6.3.1 Configuration Errors . . . . . . . . . . . . . . . . . . . . 98
6.4 Attacks on Software . . . . . . . . . . . . . . . . . . . . . . . . . 99
6.4.1 Breaking Generic Software . . . . . . . . . . . . . . . . . 100
6.4.2 Breaking Anonymizing Algorithms . . . . . . . . . . . . 102
6.4.3 Identifying Software . . . . . . . . . . . . . . . . . . . . 104
6.4.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 106
6.5 Network-based Attacks . . . . . . . . . . . . . . . . . . . . . . . 106
6.5.1 Denial of Service . . . . . . . . . . . . . . . . . . . . . . 106
6.5.2 Local Area Networks, and Local Attackers . . . . . . . . 108
6.5.3 Exit Nodes and Peers . . . . . . . . . . . . . . . . . . . . 109
6.5.4 ISP-Scale Networks . . . . . . . . . . . . . . . . . . . . 110
6.5.5 Wide Area Networks and Global Attacker . . . . . . . . . 110
6.6 Non-technical attacks . . . . . . . . . . . . . . . . . . . . . . . . 112
6.6.1 Physical Attacks . . . . . . . . . . . . . . . . . . . . . . 112
6.6.2 Legal Attacks . . . . . . . . . . . . . . . . . . . . . . . . 113
6.6.3 Social Engineering . . . . . . . . . . . . . . . . . . . . . 114
6.7 Theoretical Results on Attacks . . . . . . . . . . . . . . . . . . . 115
6.8 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
7 Considerations and Conclusion 117
7.1 Attack Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
7.1.1 Data Conversion . . . . . . . . . . . . . . . . . . . . . . 120
7.1.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
7.2 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
7.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Bibliography 127iv CONTENTS
Appendix 143
A Mailinglist Extracts: Hosting provider misbehaviour 144
A.1 Thread on OVH . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
A.2 Hosting provider kills processes . . . . . . . . . . . . . . . . . . 147
A.3 Hosting providers do not allow anonymizing services . . . . . . . 148
Index 151List of Figures
1.1 Related areas of research, all of them being sub-parts of IT security 3
1.2 Schematic relationship between targeted protection, quality of ser-
vice, and resulting protection level . . . . . . . . . . . . . . . . . 6
2.1 An example of extending an existing protocol stack with an overlay
network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 The interplay of items and entities in a cryptographic system. . . . 22
2.3 An example of an attack tree which depicts methods of illicit access
to a confidential database. . . . . . . . . . . . . . . . . . . . . . . 25
2.4 Relationship of major participating and affected entities in an anon-
ymizing network. . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.1 A graph depicting the available bandwidth for all running Tor routers,
September 2008 . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.2 Degree of relationship between deployed anonymity systems . . . 57
4.1 Flow of message in content provider’s scenario. . . . . . . . . . . 63
4.2 An example setup for Virtual Anonymous Networks . . . . . . . . 65
5.1 Overview on Properties of Attackers and their interdependencies . 80
5.2 Differences between attackers’ motivations. . . . . . . . . . . . . 84
6.1 Schematic flow of an anonymized message . . . . . . . . . . . . 92
6.2 An example HTTP-Request with a highlighted set of privacy-related
information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
6.3 Identification of the user’s browser based on its rendering capabilities105
7.1 Attacks on Networks . . . . . . . . . . . . . . . . . . . . . . . . 118
7.2 An attack tree on anonymizing networks . . . . . . . . . . . . . . 119
7.3 Example declaration in the attack-tree definition . . . . . . . . . . 121
7.4 A part of the modified attack tree. . . . . . . . . . . . . . . . . . 122
vvi LIST OF FIGURESList of Tables
2.1 A basic view of the seven ISO/OSI layers for network communication 10
2.2 A basic view of the layers of the Internet Protocol . . . . . . . . . 11
2.3 Categorizing pornographic content from plain networks and in anon-
ymizing networks . . . . . . . . . . . . . . . . . . . . . . .