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Mastering Malware Analysis

You're reading from   Mastering Malware Analysis The complete malware analyst's guide to combating malicious software, APT, cybercrime, and IoT attacks

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Product type Paperback
Published in Jun 2019
Publisher Packt
ISBN-13 9781789610789
Length 562 pages
Edition 1st Edition
Languages
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Authors (2):
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Alexey Kleymenov Alexey Kleymenov
Author Profile Icon Alexey Kleymenov
Alexey Kleymenov
Amr Thabet Amr Thabet
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Amr Thabet
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Toc

Table of Contents (18) Chapters Close

Preface 1. Section 1: Fundamental Theory FREE CHAPTER
2. A Crash Course in CISC/RISC and Programming Basics 3. Section 2: Diving Deep into Windows Malware
4. Basic Static and Dynamic Analysis for x86/x64 5. Unpacking, Decryption, and Deobfuscation 6. Inspecting Process Injection and API Hooking 7. Bypassing Anti-Reverse Engineering Techniques 8. Understanding Kernel-Mode Rootkits 9. Section 3: Examining Cross-Platform Malware
10. Handling Exploits and Shellcode 11. Reversing Bytecode Languages: .NET, Java, and More 12. Scripts and Macros: Reversing, Deobfuscation, and Debugging 13. Section 4: Looking into IoT and Other Platforms
14. Dissecting Linux and IoT Malware 15. Introduction to macOS and iOS Threats 16. Analyzing Android Malware Samples 17. Other Books You May Enjoy

Dynamic string decryption

In this case, the block of encrypted strings is not decrypted at once. Instead, each string is decrypted immediately before being used, so they are never decrypted all at the same time. In order to solve this problem, follow these steps:

  1. Find a function that's responsible for decrypting all strings.
  2. Replicate the decryptor behavior.
  3. Let the script find all the places in the code where this function is being called and then read an encrypted string that will be passed as its argument.
  4. Decrypt it and write it back on top of the encrypted one so that all the references will remain valid.
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