网络协议攻击

What’s in This Book? This book contains a mix of theoretical and practical chapters. For the practical chapters, I’ve developed and made available a networking library called Canape Core, which you can use to build your own tools for protocol analysis and exploitation. I’ve also provided an example networked application called SuperFunkyChat, which implements a userto-user chat protocol. By following the discussions in the chapters, you can use the example application to learn the skills of protocol analysis and attack the sample network protocols. Here is a brief breakdown of each chapter: Chapter 1: The Basics of Networking This chapter describes the basics of computer networking with a particular focus on TCP/IP, which forms the basis of application-level network protocols. Subsequent chapters assume that you have a good grasp of the network basics. This chapter also introduces the approach I use to model application protocols. The model breaks down the application protocol into flexible layers and abstracts complex technical detail, allowing you to focus on the bespoke parts of the protocol you’re analyzing. Chapter 2: Capturing Application Traffic This chapter introduces the concepts of passive and active capture of network traffic, and it’s the first chapter to use the Canape Core network libraries for practical tasks. Chapter 3: Network Protocol Structures Download from finelybook www.finelybook.com 24This chapter contains details of the internal structures that are common across network protocols, such as the representation of numbers or human-readable text. When you’re analyzing captured network traffic, you can use this knowledge to quickly identify common structures, speeding up your analysis. Chapter 4: Advanced Application Traffic Capture This chapter explores a number of more advanced capture techniques that complement the examples in Chapter 2. The advanced capture techniques include configuring Network Address Translation to redirect traffic of interest and spoofing the address resolution protocol. Chapter 5: Analysis from the Wire This chapter introduces methods for analyzing captured network traffic using the passive and active techniques described in Chapter 2. In this chapter, we begin using the SuperFunkyChat application to generate example traffic. Chapter 6: Application Reverse Engineering This chapter describes techniques for reverse engineering networkconnected programs. Reverse engineering allows you to analyze a protocol without needing to capture example traffic. These methods also help to identify how custom encryption or obfuscation is implemented so you can better analyze traffic you’ve captured. Chapter 7: Network Protocol Security This chapter provides background information on techniques and cryptographic algorithms used to secure network protocols. Protecting the contents of network traffic from disclosure or tampering as it travels over public networks is of the utmost importance for network protocol security. Chapter 8: Implementing the Network Protocol This chapter explains techniques for implementing the application Download from finelybook www.finelybook.com 25network protocol in your own code so you can test the protocol’s behavior to find security weaknesses. Chapter 9: The Root Causes of Vulnerabilities This chapter describes common security vulnerabilities you’ll encounter in a network protocol. When you understand the root causes of vulnerabilities, you can more easily identify them during analysis. Chapter 10: Finding and Exploiting Security Vulnerabilities This chapter describes processes for finding security vulnerabilities based on the root causes in Chapter 9 and demonstrates a number of ways of exploiting them, including developing your own shell code and bypassing exploit mitigations through return-oriented programming. Appendix: Network Protocol Analysis Toolkit In the appendix, you’ll find descriptions of some of the tools I commonly use when performing network protocol analysis. Many of the tools are described briefly in the main body of the text as well. How to Use This Book If you want to start with a refresher on the basics of networking, read Chapter 1 first. When you’re familiar with the basics, proceed to Chapters 2, 3, and 5 for practical experience in capturing network traffic and learning the network protocol analysis process. With the knowledge of the principles of network traffic capture and analysis, you can then move on to Chapters 7 through 10 for practical information on how to find and exploit security vulnerabilities in these protocols. Chapters 4 and 6 contain more advanced information about additional capture techniques and application reverse engineering, so you can read them after you’ve read the other chapters if you prefer. For the practical examples, you’ll need to install .NET Core Download from finelybook www.finelybook.com 26(https://www.microsoft.com/net/core/), which is a cross-platform version of the .NET runtime from Microsoft that works on Windows, Linux, and macOS. You can then download releases for Canape Core from https://github.com/tyranid/CANAPE.Core/releases/ and SuperFunkyChat from https://github.com/tyranid/ExampleChatApplication/releases/; both use .NET Core as the runtime. Links to each site are available with the book’s resources at https://www.nostarch.com/networkprotocols/. To execute the example Canape Core scripts, you’ll need to use the CANAPE.Cli application, which will be in the release package downloaded from the Canape Core Github repository. Execute the script with the following command line, replacing script.csx with the name of the script you want to execute.