Debugging, Disassembling, Reverse Engineering

Reversing with OBJDUMP

objdump – display plenty of information from object files. It is available in most Linux and Unix systems. It is also available in Windows through cygwin.

Display Section Headers:

objdump -h /path/to/my/object/file

Disassembling Executable Sections:

objdump -dl /path/to/my/object/file

Full Disassembling:

objdump -Dslx /path/to/my/object/file

Display Debugging Info:

objdump -g /path/to/my/object/file

Display Symbol Table contents:

objdump -t /path/to/my/object/file

Display Relocation entries:

objdump -r /path/to/my/object/file

At least one of the following switches must be given:

  -a, --archive-headers    Display archive header information
  -f, --file-headers       Display the contents of the overall file header
  -p, --private-headers    Display object format specific file header contents
  -P, --private=OPT,OPT... Display object format specific contents
  -h, --[section-]headers  Display the contents of the section headers
  -x, --all-headers        Display the contents of all headers
  -d, --disassemble        Display assembler contents of executable sections
  -D, --disassemble-all    Display assembler contents of all sections
  -S, --source             Intermix source code with disassembly
  -s, --full-contents      Display the full contents of all sections requested
  -g, --debugging          Display debug information in object file
  -e, --debugging-tags     Display debug information using ctags style
  -G, --stabs              Display (in raw form) any STABS info in the file
  -W[lLiaprmfFsoRt] or
                           Display DWARF info in the file
  -t, --syms               Display the contents of the symbol table(s)
  -T, --dynamic-syms       Display the contents of the dynamic symbol table
  -r, --reloc              Display the relocation entries in the file
  -R, --dynamic-reloc      Display the dynamic relocation entries in the file
  @<file>                  Read options from <file>
  -v, --version            Display this program's version number
  -i, --info               List object formats and architectures supported
  -H, --help               Display this information

The following switches are optional:

  -b, --target=BFDNAME           Specify the target object format as BFDNAME
  -m, --architecture=MACHINE     Specify the target architecture as MACHINE
  -j, --section=NAME             Only display information for section NAME
  -M, --disassembler-options=OPT Pass text OPT on to the disassembler
  -EB --endian=big               Assume big endian format when disassembling
  -EL --endian=little            Assume little endian format when disassembling
      --file-start-context       Include context from start of file (with -S)
  -I, --include=DIR              Add DIR to search list for source files
  -l, --line-numbers             Include line numbers and filenames in output
  -F, --file-offsets             Include file offsets when displaying information
  -C, --demangle[=STYLE]         Decode mangled/processed symbol names
                                  The STYLE, if specified, can be `auto', `gnu',
                                  `lucid', `arm', `hp', `edg', `gnu-v3', `java'
                                  or `gnat'
  -w, --wide                     Format output for more than 80 columns
  -z, --disassemble-zeroes       Do not skip blocks of zeroes when disassembling
      --start-address=ADDR       Only process data whose address is >= ADDR
      --stop-address=ADDR        Only process data whose address is <= ADDR
      --prefix-addresses         Print complete address alongside disassembly
      --[no-]show-raw-insn       Display hex alongside symbolic disassembly
      --insn-width=WIDTH         Display WIDTH bytes on a single line for -d
      --adjust-vma=OFFSET        Add OFFSET to all displayed section addresses
      --special-syms             Include special symbols in symbol dumps
      --prefix=PREFIX            Add PREFIX to absolute paths for -S
      --prefix-strip=LEVEL       Strip initial directory names for -S
      --dwarf-depth=N        Do not display DIEs at depth N or greater
      --dwarf-start=N        Display DIEs starting with N, at the same depth
                             or deeper
      --dwarf-check          Make additional dwarf internal consistency checks.

Supported targets:

elf64-x86-64 elf32-i386 elf32-x86-64 a.out-i386-linux pei-i386 pei-x86-64 elf64-l1om elf64-k1om elf64-little elf64-big elf32-little elf32-big pe-x86-64 pe-bigobj-x86-64 pe-i386 plugin srec symbolsrec verilog tekhex binary ihex

Supported architectures:

i386 i386:x86-64 i386:x64-32 i8086 i386:intel i386:x86-64:intel i386:x64-32:intel i386:nacl i386:x86-64:nacl i386:x64-32:nacl l1om l1om:intel k1om k1om:intel plugin

Disassembler Options(for use with the -M switch):

  x86-64      Disassemble in 64bit mode
  i386        Disassemble in 32bit mode
  i8086       Disassemble in 16bit mode
  att         Display instruction in AT&T syntax
  intel       Display instruction in Intel syntax
              Display instruction in AT&T mnemonic
              Display instruction in Intel mnemonic
  addr64      Assume 64bit address size
  addr32      Assume 32bit address size
  addr16      Assume 16bit address size
  data32      Assume 32bit data size
  data16      Assume 16bit data size
  suffix      Always display instruction suffix in AT&T syntax