anyone interested in cracking crackme's?

[lepricaun]

something went wrong! i'm fixing it atm, try again in about half an hour

sorry bout that!

[EDIT] view attachment for the new version:[/EDIT]

[sec_ware]

Hi

Well, lepricaun, crackit_8.exe was a challenge.
I have to admit that I am amazed how fast you
increased your skills. When did you start to learn
asm/securing codes? 10-04-2004 11:02 PM was
your first post in this thread. That's not even a
month ago.

This time, there were several layers of protection:
- disassembler-killer: encoded and packed code, ie
the executable is selfmodifying.
- debugger-killers: there were 2 techniques used to
make the use of the debugger difficult. First, exceptions
break the flow of the code. Second, 0xCC recognition
locks the tracing in an infinit loop.
- logic-killer: the algorithm used to create the serial number
based on the username is non-trivial and needs persistency
to be REd.

How to deal with that crackit_8.exe:
- cracking is almost not possible. First, the "file is corrupt"-check has
to be circumvented. Second, a hex-change in the code might have unpredictable
consequences.
- hence, a serial key-generator.

Luckily, no minimal username-length is required. Hence, we can
deduce the algorithm for the case strlen(username)<=2, which is
much simpler than the other cases.

Find attached the keygenerator, the source code of it and the
essential assembler part of the program.

How to further improve:
- strlen(username)>=6
- improve the difficulty of the algorithm
- use executables which makes use of several threads
- prevent setting of breakpoints (there are only a few tricks)
- not much more, as I know of, to be honest.


Cheers

[White Scorpion]

Hi Sec_ware, well, since you have posted your keygenerator here, i will pm you with mine.

and as i stated before, it is not me with all the tricks, it is a simple packed that i have downloaded to pack my code

i will send you the sourcecode of crackit_8 and i will add you to the site