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Burningmace
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PostPosted: Tue Sep 16, 2008 6:30 pm    Post subject: Reply with quote

I still don't understand how this bypassed the hash checks. If you alter the variable the checks should fail.
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Noz3001
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PostPosted: Tue Sep 16, 2008 6:32 pm    Post subject: Reply with quote

Hehe, go re-check your checks and ill look out for another revision tomorrow.
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Burningmace
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PostPosted: Tue Sep 16, 2008 7:24 pm    Post subject: Reply with quote

I've updated the code and I'm now doing some funky stuff with the value. I attempted your method and I can't get it to work now (whereas I did in the old version). Test it out Smile
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rapion124
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PostPosted: Tue Sep 16, 2008 8:05 pm    Post subject: Reply with quote

Wow. All these things fail. As long as people have access to the assembly code of your program, they can defeat any protection. All they need to do is trace onto your decryption routine and either recreate it or call it.

You should do some integrity checking on each instance of your class. Even that can be patched with a simple CreateThread() hook.

Also, why go through all this trouble? Why not just use the Crypto APIs and encrypt/decrypt the value? The advantage of using them is it is very hard to crack the algorithm as they are usuallly very complex. But, a simple hook will defeat this too.

Easiest way is to get a very powerful PE packer. That will stop people from debugging your code.
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Flyte
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PostPosted: Tue Sep 16, 2008 11:20 pm    Post subject: Reply with quote

rapion124 wrote:
Easiest way is to get a very powerful PE packer. That will stop people from debugging your code.


Which are less useful than you may think.
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Noz3001
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PostPosted: Wed Sep 17, 2008 3:35 am    Post subject: Reply with quote

Burningmace wrote:
I've updated the code and I'm now doing some funky stuff with the value. I attempted your method and I can't get it to work now (whereas I did in the old version). Test it out Smile


Exactly the same =|.

Code:
695A4615:
 mov ecx,32000000
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Burningmace
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PostPosted: Wed Sep 17, 2008 6:43 am    Post subject: Reply with quote

Ok, now I'm really lost.

Also, what's with that 32000000 value? I don't get how that makes it 5000.
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Noz3001
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PostPosted: Wed Sep 17, 2008 8:38 am    Post subject: Reply with quote

Burningmace wrote:
Ok, now I'm really lost.

Also, what's with that 32000000 value? I don't get how that makes it 5000.


I got the value by testing them in one of the registers.

I ended up making this one of my daily projects XD. http://forum.cheatengine.org/viewtopic.php?p=2857542#2857542


Last edited by Noz3001 on Wed Sep 17, 2008 3:39 pm; edited 2 times in total
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G0DFATHER
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PostPosted: Wed Sep 17, 2008 1:14 pm    Post subject: Reply with quote

wow noz3001 ur smart anyways how do that with ollydbg mind posting me a lnk to a tut.
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Burningmace
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PostPosted: Wed Sep 17, 2008 6:50 pm    Post subject: Reply with quote

I've added a serialization integrity check. I'm not sure if this will get round your modification but have a go.
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Noz3001
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PostPosted: Thu Sep 18, 2008 2:16 am    Post subject: Reply with quote

Burningmace wrote:
I've added a serialization integrity check. I'm not sure if this will get round your modification but have a go.


Same, address is now 69B34617.
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Burningmace
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PostPosted: Thu Sep 18, 2008 6:11 am    Post subject: Reply with quote

I don't know how you're managing that... are you sure you're not just tripping out one of the jump operations or something? Setting the internal value to 32000000 every time makes no sense whatsoever - when it's xor'ed with the random value it'll come out with something completely different every single time you run it.

For example:
internalValue = 32000000
randomValue = -134905492
realValue = -165820052

You don't need me to tell you that -165820052 isn't 5000.

Not only that, but there are six separate checks (things like checking internalValue % 8 against a stored value) for integrity and the entire class is serialised and hashed. If the memory changes, shouldn't the serialised data change too?
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Trucido
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PostPosted: Thu Sep 18, 2008 6:30 am    Post subject: Reply with quote

Burningmace, you might wanna check out the CrackMe subsection of general programming.

And SF or Safcow Might wanna bump this over there.

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SFP+
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PostPosted: Thu Sep 18, 2008 8:39 am    Post subject: Reply with quote

Trucido wrote:
Burningmace, you might wanna check out the CrackMe subsection of general programming.

And SF or Safcow Might wanna bump this over there.


Done.
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