[CrackMe] s!mple CrackMe v0.3

[simple]

Hey guys, welcome to my third crack me!

 

Compiler: mingw

  Packer:  Hopefully the next one will have this

Difficulty: ~3/10

    Rules: Anything goes. Wrote this w/patchers in mind, but serial phishing/keygenning would be great too

 

 

Enjoy, feedback is welcome and thanks for reversing!

CMv0.3.rar

[wxfengyun]

i found that this crackme uses CreateWindowExA to show "incorrect!" text.

At the same time, the "incorrect!" text is on the heap, and decrypt at runtime.

but i didn't find where is the judge jz or jnz, it is hide so deep, and i counldn't crack it now.

Can someone give me some clues?

[kao]

Name: kao!

Serial: 6.20383688w

Obviously, it's only valid for my machine..

Hint that will save you lots of time and effort:

nm.exe -n --demangle CMv0.3.exe

[wxfengyun]

Name: kao!

Serial: 6.20383688w

Obviously, it's only valid for my machine..

Hint that will save you lots of time and effort:

nm.exe -n --demangle CMv0.3.exe

Can you tell me some more details about finding serial?  I'm a newbie and i did not have nm.exe, i am in windowsXP +OllyDbg, it's so confused for me to understand its' verification algorithm.

 

Thank you very very much!

[redblkjck]

Install MinGW and you will have nm.exe     You will want to pipe the output to a text file.

There are 4 parts to create the serial and each is checked individually before going to the next part.    It is machine specific.

[simple]

I just had someone else serial fish it yesterday too : )

 

Each cmp is obfuscated wxfengyun, try to use nm.exe. There are 4 important parts to the constuction of the serial, where it's compared against 3 different variables that (should be) unique to each machine (can anyone ID what exactly these parts are?) The final check (the 4th) should be a little more "normal" than the previous 3.

 

Currently writing the next keygen, hopefully it will keep everyone busy for another 10 days!  Thanks for reversing!

[wxfengyun]

Install MinGW and you will have nm.exe     You will want to pipe the output to a text file.

There are 4 parts to create the serial and each is checked individually before going to the next part.    It is machine specific.

thank you very much, and i find the serial of my machine now. the algorithm is so complicated, i spend so much time to debug it.

[kao]

Small keygen+source attached. Didn't test it much but it should work just fine..

Have fun,

kao!

P.S. It kept me busy for just a few hours, but it's still a nice challenge!

keygen.rar

[redblkjck]

@kao!   worked fine on my machine.   
The 4 specific parts are noted in the kg source if anyone else stuck.

 

It can be patched to accept any serial at the REPE CMPS location.  Also the serial can be sniffed out in ascii at the same location, if user aware of the fake checks.

[simple]

kao - keygen works perfectly. Written in asm too... impressive!

 

wxfengyun - Look at the keygen, the core algorithym itself is very simple : )

 

Thanks for the feedback everyone, was a pleasure watching y'all crack.