IDA Pro Book Chapter Two! TOOL TIME!

BTW, I'm not about to retype this whole IDA book (obviously), so you should definitely buy it if you have not already.

I am on chapter 2 and this chapter is all about TOOLS. Below is a list and a few points on the tools mentioned in this chapter. I learned about a few new tidbits like magic numbers and name mangling and what tools are the best for what situation.
  • FILE
    • included in all linux like OS's (this includes osx btw, and CYGWIN for Windows)
    • tries to guess at the file's type
    • uses magic numbers (certain bit patterns that are standard to certain files)
    • usage - 'file filename'
  • PE Tools
  • PEiD
    • Windows based 
    • identifies entry point
    • Compiler and/or Packers used
    • usage - open a binary file in PEiD gui
    • http://peid.info
  • NM
    • available in linux (includes OSX)
    • lists symbols from object files
    • basically lists function and variable names
    • 'man nm' has more
    • usage 'nm filename'
  • LDD
    • linux type operating systems (does NOT include OSX, see next tool)
    • stands for list dynamically dependencies
    • works on dynamically linked binaries (see below for what this means)
    • usage 'ldd filname'
  • objdump
    • runs on linux and cygwin(not OSX)
    • dumps out LDD information and way more
    • very flexible, with lots of command line options
    • Includes: headers, debugging info, symbol info, disassembly listing (dead listing)
    • usage objdump filename
  • otool
    • runs on OSX
    • similar to objdump but for OSX Mach-O binaries
    • displays dynamically linked dependencies like ldd with the -L switch
    • run otool with no arguments for a list of all switches
  • dumpbin
    • runs on Windows, is included in Visual Studio
    • can extract lots of info from PE files, including: symbols, imported function names, exported function names, and disassembly listing 
    • output is usually pretty, IMO
    • usage dumpbin /dependents filename.exe --lists dependencies similar to ldd. 
  • c++filt
    • runs on linux (was native on OSX too) 
    • addresses mangled name problem, (see special note below)
    • treats input as a mangled name and returns more usefull function information
    • usage pipe nm output to c++filt. ie. nm filename | grep functionname | c++filt
  • strings
    • runs on linux, osx, cygwin (also an .exe windows version out there somewhere too)
    • simply returns any string data in any file
    • useful for getting a quick idea of a file, but can contain loads of garbage data
    • usage strings filename
    • to scan the complete binary (not just initialized sections) use the -a switch
    • use -t to get the hex offset of the string locations
    • use -e for Unicode strings 

Special note on magic numbers
  • 0xCA FE BA BE is standard for all Java .class files
  • 0x4D 5A ascii MZ is standard for all Windows PE Executables
  • 0xFF D8 at the beginning, then 0x4A 46 49 46 ascii JFIF is standard in all JPEG files
Special note on Dynamic and Static Linking:
  • Static linking puts copies of all the required libraries into the file. 
    • PRO - functions calls are faster and you don't need the libraries on your system
    • CON - binary is larger and difficulty upgrading the software when components change
  • Dynamic is the opposite. Library files are specified in the binary and loaded in at run time 
  • Dynamic linking is the default
  • You can specify static linking in gcc with the --static switch
Special note on Function Overloading and Name Mangling:

  • When you overload a function, that is, have multiple functions with the same names that perform different tasks based on the number or type of arguments given, the compiler has to handle this in a unique way. It assigns random names to each function in a not that really random way. More on name mangling can be found at wikipedia! 

That is it for chapter 2. I should also mention that if you are having trouble getting through a book. Blogging your notes like I am doing right now is an awesome motivator and keeps your mind entertained and engaged. You may cover the material more slowly, but retention is greatly increased.

Best of luck world.

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