add symbols back into a stripped ELF binary (~strip)
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Latest commit c745c36 May 17, 2017

README.md

dress

add symbols back into a stripped ELF binary

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Usage

./dress <in-file> <out-file> <sym-file> [-v]

  • in-file: path to the input (stripped) ELF binary
  • out-file: path to the desired output location of the dressed binary; this file will have the same permissions as in-file
  • sym-file: path to the symbol file
  • -v: turns on verbose output; this is generally not helpful unless something is going wrong

Example

$ gcc test.c
$ readelf -s a.out
Symbol table '.symtab' contains 70 entries:
...
62: 0000000000601044     4 OBJECT  GLOBAL DEFAULT   26 counter
64: 0000000000400593    54 FUNC    GLOBAL DEFAULT   14 main
69: 0000000000400566    45 FUNC    GLOBAL DEFAULT   14 test
$ strip a.out -o b.out
$ readelf -s b.out
$ dress b.out c.out a.syms
$ readelf -s c.out
Symbol table '.symtab' contains 3 entries:
0: 0000000000601044     0 OBJECT  LOCAL  DEFAULT   25 counter
1: 0000000000400593     0 FUNC    LOCAL  DEFAULT   14 main
2: 0000000000400566     0 FUNC    LOCAL  DEFAULT   14 test

Building

gcc dress.c libelf.c logging.c -o dress

Symbol file format

Currently, there are two types of symbols: global variables and function names. By default, all symbols are globals. However, adding parentheses after the symbol name designates it as a function. The address of the symbol is indicated after the @ sign with an asterix. The address can be in either base 16 or base 10.

Example a.syms:

counter @ *0x601044
main() @ *0x400593
test() @ *0x400566

Known issues and limitations

  • While Binary Ninja handles most global variables as intended, IDA has issues recognizing the symbol names. This is most likely due to the improper labeling of corresponding section for their symbols. Ability to specify sections for symbols will be added in the future.
  • This version of dress is only compatible with 64 bit ELF files.