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 Forums >>  Debuggers  >>  Reverse a WinRAR packed exe

Topic created on: May 13, 2012 07:23 CDT by talss .

Hello, I have a crackme exercise which is a console application packed with winrar.

I have unpacked the exe and when i try using it by just executing it, everything is fine.

But when i try reversing it using ollydbg(the same file), it still says that the entry point is outside the PE, and at some part while debugging it has an access violation.

What may be the problem?

Thank you very much.

  DriEm   May 15, 2012 13:07.49 CDT
As the EXE file runs well after you have unpacked it, the problem should not be related to WinRAR.
Maybe, the EXE contains TLS callback functions, these are executed before the EXE's entry point is reached. Have a look at waliedassar's blog post on TLS callbacks:

http://waleedassar.blogspot.de/2010/10/quick-look-at-tls-callbacks.html

  NirIzr     May 17, 2012 11:57.22 CDT
it doesn't have to be tls, but there's probably some kind of anti-debugging that detects the executable is being debugged and terminates.
you should analyze the code leading to the access violation to determine why exactly the crush happens...
if you could give us more info as to what happens before the crush we might recognize the anti debugging tricks.

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