The MASM Forum

Does Olly trap this infinite loop automatically ?
I even used jnz.

invoke IsDebuggerPresent ; running in the context of a debugger, the return value is nonzero

jz      short continue_initialization_1

jmp     short infinite_loop_1


infinite_loop_1:
   
jmp infinite_loop_1

continue_initialization_1:

---------------------------------------------

Once started, Olly runs an application until an exception occurs or you paused it.
Also, it is not specified whether IsDebuggerPresent (or any other API) set or clear the zero flag ;-)

invoke IsDebuggerPresent ; running in the context of a debugger, the return value is nonzero
test eax,eax

infinite_loop_1:
jnz infinite_loop_1

Thanks, the prog works but I am confused.

EAX has zero when run under Olly ?

i just went by your comment   :P

Quoteinvoke IsDebuggerPresent ; running in the context of a debugger, the return value is nonzero

here is the MSDN doc...

QuoteReturn value

If the current process is running in the context of a debugger, the return value is nonzero.

If the current process is not running in the context of a debugger, the return value is zero.

The call to IsDebuggerPresent is easily patched to always return false; it could even be considered standard practice.

Stop wasting your time ::)

Right Tedd

IsDebuggerPresent is only an api the get the BeingDebuged from the Peb