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The third crackme

- no patching please
- find the right code and/or code keygen/loader

Have fun

Difficulty: 2 - Needs a little brain (or luck)
Platform: DOS
Language: Assembler

Published: 12. Oct, 2005
Downloads: 497

Rating

Votes: 3
Crackme is quite bad.

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Discussion and comments

NoRG
12. Oct 2005
sas0, I see data for checking generates with every time with random timer values. Or exists some hidden correlation? :)
|sas0|
Author
13. Oct 2005
If you carefully watch this "random" data you'll see that some bytes of data are evrytime almost the same I think that there is no hidden correlation but I think that it can be predictable from algo which is "random" generated...or you can code loader/dumper to dump this data and calculate serial from it
NoRG
15. Oct 2005
I don't think so. I've dumped blocks few times and them is different everytime. I can calculate serial for current run, but on next run it is not valid. Maybe here need pure DOS, who knows, I run under WINXPsp2 with TD and TR.
Anyway, I want look at keygen. I think it's not possible without ask code. Patch is right and fast solution :)
|sas0|
Author
18. Oct 2005
If you run it under debuger then there is a big posibility that it will be totaly different evry time...try to patch the prog so that it shows data on screen..you'll see that without a debuger some parts of data are almost evrytime the same
|sas0|
Author
18. Oct 2005
...and yes the crackme was tested under win9x and win2000 so I'm not sure if it acts different under XP....try to make self-keygen instead :) patch is too easy
pants
29. Dec 2005
I have to agree with NoRG - this appears to be an odd crackme, unless we're both missing something very obvious.

Easy to create self-keygen (or loader) - but for what purpose? Patch in this case is equally valid due to randomness of the init vector.

Still, nice to see a DOS crackme - thanks |sas0| :)
|sas0|
Author
29. Dec 2005
Thanks pants....well I gues I fucked up this crackme a little bit :) thanks anyway to try this crackme....next crackme I hope it will be more difficulty and chalenging then this one....anyway happy new year folks
pants
29. Dec 2005
Don't be so hard on yourself - other than the randomness of the timer it had the makings of an interesting crackme! I'm very intrigued though - you say there is little change in the timer results on your system? This is interesting... Anything special about your system that would produce so little timer variance? You seem familiar with the traditional usage of such code (and probably realise the implications of low timer variance on them...)

Anyway - thanks again and keep them coming :)

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