Wednesday, March 09 2005 @ 10:06 PM CET Contributed by: detten Views: 4763
Level : beginner
An alternative to writing a keygenerator is making an inline keygenerator. If the target can be serial fished, it can be inline keygenned. An example on a simple crackme.
In this tutorial we will crack Rith's crackme, and make an internal keygenerator
What is an internal keygenerator? Well, I call it a 'keygen for lazy reversers'
The idea is to change the target program in a way that it displays the correct
serial for you.
(**) Saves each byte of the calculated serial to address in EDX+Counter
(***) Add a NULL string terminator to the Serial
(****) Display serial in the MessageBox
When we change ** and *** and **** we have made a very basic, but working
Now enter your name and a serial with the same length, hit the Register-button
... tada ... There is your valid serial!
Have you noticed that we only had to change 14 bytes to change the proggy
to an internal keygen? As I said, this is great for lazy programmers :)
To complete this keygen, let's change the program so that we don't have
to enter any serial.
Nop the jump at (*), and we're done!
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