Code Engineering - TCP/IP Swapper v3.00
Finding Correct Serial Numbers
Hardcoded Registration Keys
Please Read The Disclaimer
Since this program's protection is so pathetic, it didn't justify writing an essay. But, I'll show you how to find the serial number in Soft-Ice so it's not a complete waste.
Prepare To Crack:
Run the program (swapper.exe), and you'll notice a nag screen telling you how many uses you have (only 15! this thing NEEDS to be cracked!), and a text box to enter a serial number.
Let's see if we can "fish" our valid serial number in Soft-Ice. The most common breakpoints for 32-bit programs are "GetDlgItemTextA" and "GetWindowTextA". To save you time, GetWindowTextA is the breakpoint we need.
Making The Crack:
Enter a dummy serial number,
and press Cntrl+D to enter Soft-Ice. Set a breakpoint on GetWindowTextA
(BPX GETWINDOWTEXTA). Press Cntrl+D or X to exit back to the program,
and click the "Register" button. Soft-Ice pops up. Press
F11 once to exit from the code, and you should be here:
Now we need to step through
the code using F10, until we see something interesting. Stop at
the following piece of code:
Step through the line
"PUSH 0043E154". Now let's see what this location
holds. Display the location by typing: d 0043E154. Now use
your Alt+Down Arrow keys to scroll down just a few times, and you'll
see the following in the data window:
Could the highlighted number above possibly be our serial number? Disable your breakpoint by typing bc * and write this number down. Press Cntrl+D or X to exit back out the program. Press "OK" on the invalid serial number dialog box, and enter the number into the text box... press "Register", and voila! registered!
Now, due to the strange location of this serial number, we assume that this must be a hardcoded serial number (coded directly into the program - stupid!). To confirm our suspicions, let's disassemble swapper.exe with Wdasm.
Once disassembled, look
at the string references ("Refs", "String Data References"). After
scrolling down for just a bit, you'll find the number. Double
click on it, and you'll land at the following piece of code:
There's the routine that checks our serial number! Hardcoded, and ready for anyone to use.
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