home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Reverse Code Engineering RCE CD +sandman 2000
/
ReverseCodeEngineeringRceCdsandman2000.iso
/
RCE
/
E_bliss
/
eb_tut5.txt
< prev
next >
Wrap
Text File
|
2000-05-25
|
5KB
|
142 lines
Tutorial Number 5
Written by Etenal Bliss
Email: Eternal_Bliss@hotmail.com
Date written: 23rd Jan 1999
Program Details:
Name: CrackMe v4.0
Author: Magenta
Language: Visual Basic
Tools Used:
NuMega SmartCheck 6.01
Cracking Method:
Analyzing Data in SmartCheck
Viewing Method:
Use Notepad with Word Wrap switched on
Screen Area set to 800 X 600 pixels (Optional)
__________________________________________________________________________
About this protection system
No disabled function. Protection is based on a 8 digit combination which
must satisfy an algorithm.
__________________________________________________________________________
The Essay
As this is a tutorial for newbies, I'll go into details about how I go about
cracking the program. I suggest that you read this tutorial first.
When you have completed the tutorial, leave this tutorial open and follow
the instructions while using SmartCheck. Re-do it once more after you have
completed the step by step guide...
__________________________________________________________________________
Data Analysis in SmartCheck
Run SmartCheck. Load the program using it by using "File", "Open"
and choose Crackme#4.exe
If this is your first time using SmartCheck, do the following:-
Under Program Settings:-
Error Detection: "tick" all boxes except "Report errors immediately".
Advanced: "tick" first 4 boxes.
Make sure "Suppress system API and OLE calls" is not "ticked".
Reporting: All boxes "ticked" except for "Report MouseMove events
from OCX controls"
**I have captured the images of the three boxes for better reference. They are
available on http://crackmes.cjb.net
Run Crackme#4.exe in SmartCheck by pressing F5. Type in any registration
code you want. (I used 26398457) Then click "Ok". You will get a
"You failed, try again loser" message. Exit the program.
Ok. You will see a few lines in the left window. Look for Command1_Click.
**This is the subroutine in VB that is called when you click on the
"Ok" button.
Click on Command1_Click. Under "View" in SmartCheck, choose
"Show All Events" and "Show Arguments".
**This is also capture in a file called setting4.jpg file on
http://crackmes.cjb.net
**Make sure you click on Command1_Click first or you will be lost
in a sea of codes!!!
Click on the + sign next to Command1_Click to expand the threads
under it. You can go through every single thread if you want.
I'm saving you time now by telling you what to look for...
Note: what I entered is 26398457
Interesting lines include:
1) __vbaVarMul(VARIANT:String:"2", VARIANT:String:"6") ...
**1st number multipied by 2nd = 12
2) __vbaVarAdd(VARIANT:String:"3", VARIANT:String:"9") ...
**3rd number joined with 4th = 39 and not 12!!
3) __vbaVarSub(VARIANT:Double:12, VARIANT:String:"39") ...
**Answer from step 1 subtracted by answer from step 2 = -27
4) __vbaVarMul(VARIANT:String:"8", VARIANT:String:"4") ...
**5th number multiplied by 6th number = 32
5) __vbaVarAdd(VARIANT:Double:-27, VARIANT:Double:32) ...
**Answer from step 3 plus answer from step 4 = 5
6) __vbaVarAdd(VARIANT:Double:5, VARIANT:String:"5") ...
**Answer from step 5 plus 7th number = 10
7) __vbaVarSub(VARIANT:Double:10, VARIANT:String:"7") ...
**Answer from step 6 subtracted by 7 = 3
3rd line from step 7 you will see
8) __vbaVarTstEq(VARIANT:Double:3, VARIANT:Const Integer:10)...
**Answer from step 7 is compared to 10
Overall formula for the protection scheme:
((a * b) - (c & d)) + (e * f) + g - h = 10
where a = 1st number, b = 2nd number, c = 3rd number etc...
So, by understanding this, we can create our own correct serial.
For example, g = 1 and h = 1
So, ((a * b) - (c & d)) + (e * f) = 10
If (a * b) = 16, (c & d) = 12 and (e * f) = 6, we will get 10
So, a = 2, b = 8, --> 2 * 8 = 16
c = 1, d = 2, --> 1 & 2 = 12
e = 2, f = 3, --> 2 * 3 = 6
So, (16 - 12) + 6 = 10
One of the correct serial will be 28122311
__________________________________________________________________________
Final Notes
This tutorial is dedicated to all the newbies like me. I've tried to
explain everything in details.
And because I'm a newbie myself, I may have explained certain things wrongly
So, if that is the case, please forgive me.
My thanks and gratitude goes to:-
The Sandman
All the writers of Cracks tutorials