format PE GUI
entry start

include 'win32a.inc'

section '.text' code readable executable

  start:
    ; get PEB
    mov eax, [fs:0x30]
    ; compare BeingDebugged flag of PEB
    cmp byte [eax + 2], 0
    je  goodboy

    ; show bad boy
    push    0       ; type MB_OK
    push    _badcaption ; dialog title
    push    _badmessage ; message
    push    0       ; no owner window
    call    [MessageBoxA]
    jmp exit

  goodboy:
    ; show good boy
    push    0       ; type MB_OK
    push    _goodcaption    ; dialog title
    push    _goodmessage    ; message
    push    0       ; no owner window
    call    [MessageBoxA]

   exit:
    push    0       ; success
    call    [ExitProcess]

section '.data' data readable writeable

  _badcaption db 'I got you!',0
  _badmessage db 'Stop debugging me!',0
  _goodcaption db 'Everything is fine!',0
  _goodmessage db 'Have a good day!',0

section '.idata' import data readable writeable

  library kernel,'KERNEL32.DLL',\
      user,'USER32.DLL'

  import kernel,\
     ExitProcess,'ExitProcess'

  import user,\
     MessageBoxA, 'MessageBoxA'

section '.reloc' fixups data readable discardable