Table of Contents for
Learning Linux Binary Analysis

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition Learning Linux Binary Analysis by Ryan elfmaster O'Neill Published by Packt Publishing, 2016
  1. Cover
  2. Table of Contents
  3. Learning Linux Binary Analysis
  4. Learning Linux Binary Analysis
  5. Credits
  6. About the Author
  7. Acknowledgments
  8. About the Reviewers
  9. www.PacktPub.com
  10. Preface
  11. What you need for this book
  12. Who this book is for
  13. Conventions
  14. Reader feedback
  15. Customer support
  16. 1. The Linux Environment and Its Tools
  17. Useful devices and files
  18. Linker-related environment points
  19. Summary
  20. 2. The ELF Binary Format
  21. ELF program headers
  22. ELF section headers
  23. ELF symbols
  24. ELF relocations
  25. ELF dynamic linking
  26. Coding an ELF Parser
  27. Summary
  28. 3. Linux Process Tracing
  29. ptrace requests
  30. The process register state and flags
  31. A simple ptrace-based debugger
  32. A simple ptrace debugger with process attach capabilities
  33. Advanced function-tracing software
  34. ptrace and forensic analysis
  35. Process image reconstruction – from the memory to the executable
  36. Code injection with ptrace
  37. Simple examples aren't always so trivial
  38. Demonstrating the code_inject tool
  39. A ptrace anti-debugging trick
  40. Summary
  41. 4. ELF Virus Technology �� Linux/Unix Viruses
  42. ELF virus engineering challenges
  43. ELF virus parasite infection methods
  44. The PT_NOTE to PT_LOAD conversion infection method
  45. Infecting control flow
  46. Process memory viruses and rootkits – remote code injection techniques
  47. ELF anti-debugging and packing techniques
  48. ELF virus detection and disinfection
  49. Summary
  50. 5. Linux Binary Protection
  51. Stub mechanics and the userland exec
  52. Other jobs performed by protector stubs
  53. Existing ELF binary protectors
  54. Downloading Maya-protected binaries
  55. Anti-debugging for binary protection
  56. Resistance to emulation
  57. Obfuscation methods
  58. Protecting control flow integrity
  59. Other resources
  60. Summary
  61. 6. ELF Binary Forensics in Linux
  62. Detecting other forms of control flow hijacking
  63. Identifying parasite code characteristics
  64. Checking the dynamic segment for DLL injection traces
  65. Identifying reverse text padding infections
  66. Identifying text segment padding infections
  67. Identifying protected binaries
  68. IDA Pro
  69. Summary
  70. 7. Process Memory Forensics
  71. Process memory infection
  72. Detecting the ET_DYN injection
  73. Linux ELF core files
  74. Summary
  75. 8. ECFS – Extended Core File Snapshot Technology
  76. The ECFS philosophy
  77. Getting started with ECFS
  78. libecfs – a library for parsing ECFS files
  79. readecfs
  80. Examining an infected process using ECFS
  81. The ECFS reference guide
  82. Process necromancy with ECFS
  83. Learning more about ECFS
  84. Summary
  85. 9. Linux /proc/kcore Analysis
  86. stock vmlinux has no symbols
  87. /proc/kcore and GDB exploration
  88. Direct sys_call_table modifications
  89. Kprobe rootkits
  90. Debug register rootkits – DRR
  91. VFS layer rootkits
  92. Other kernel infection techniques
  93. vmlinux and .altinstructions patching
  94. Using taskverse to see hidden processes
  95. Infected LKMs – kernel drivers
  96. Notes on /dev/kmem and /dev/mem
  97. /dev/mem
  98. K-ecfs – kernel ECFS
  99. Kernel hacking goodies
  100. Summary
  101. Index

Chapter 3. Linux Process Tracing

In the last chapter, we covered the internals of the ELF format and explained its internal workings. In Linux and other Unix-flavored OSes that use ELF, the ptrace system call goes hand in glove with analyzing, debugging, reverse engineering, and modifying programs that use the ELF format. The ptrace system call is used to attach to a process and access the entire range of code, data, stack, heap, and registers.

Since an ELF program is completely mapped in a process address space, you can attach to the process and parse or modify the ELF image very similarly to how you would do this with the actual ELF file on disk. The primary difference is that we use ptrace to access the program instead of using the open/mmap/read/write calls that would be used for the ELF file.

With ptrace, we can have full control over a program's execution flow, which means that we can do some very interesting things, ranging from memory virus infection and virus analysis/detection to userland memory rootkits, advanced debugging tasks, hotpatching, and reverse engineering. Since we have entire chapters in this book dedicated to some of these tasks, we will not cover each of these in depth just yet. Instead, I will provide a primer for you to learn about some of the basic functionality of ptrace and how it is used by hackers.

The importance of ptrace

In Linux, the ptrace(2) system call is the userland means of accessing a process address space. This means that someone can attach to a process that they own and modify, analyze, reverse, and debug it. Well-known debugging and analysis applications such as gdb, strace, and ltrace are ptrace assisted applications. The ptrace command is very useful for both reverse engineers and malware authors.

It gives a programmer the ability to attach to a process and modify the memory, which can include injecting code and modifying important data structures such as the Global Offset Table (GOT) for shared library redirection. In this section, we will cover the most commonly used features of ptrace, demonstrate memory infection from the attacker's side, and process analysis by writing a program to reconstruct a process image back into an executable. If you have never used ptrace, then you will see that you have been missing out on a lot of fun!