Software Reverse Engineering [PrimaSoft Dialer v1.4]

Reverse Code Engineering - PrimaSoft Dialer v1.4 Finding Correct Serial Numbers Author: Volatility

Please Read The Disclaimer Before Continuing.

Target	PrimaSoft Dialer v1.4 - (32pspd.zip) - 440,935 bytes (This Method Will Work For MOST Software At www.primasoft.com)
Location	http://www.primasoft.com/demo/32pspd.zip
Protection(s)	User Name/Serial Number/30-Day Time Limit
Tools Needed	Soft-Ice (Any Version)
Level	(X) Beginner ( ) Intermediate ( ) Advanced ( ) Expert

Prepare To Crack:

My entire motive for cracking this program, is that PrimaSoft puts out some goofy ass software that literally annoys the piss outta me! This program is about the most normal one of the bunch!

Anyway... run the program, and you'll see a nag screen, telling you that you have 30 days to evaluate the product. When the program comes up, you'll see there is no place to enter your registration information. Hmm... a hidden registration? Click on the "Exit" button, and there's our answer, another nag screen, but this one with the option to enter registration.

Go to the registration screen and enter some test data. For this program, let's try the HMEMCPY function. Press Cntrl+D to enter Soft-Ice, and set a breakpoint on HMEMCPY (BPX HMEMCPY).

Making The Crack:

Press Cntrl+D again to exit out of Soft-Ice, and click on the "Ok" button. Soft-Ice breaks. Press F11 to get into the code. You'll see down on the line above the command window the string "USER(0A). This isn't where we want to be, so step through the code using F10 until you see the string "PSDIAL!CODE" on the line. You should now be here:

0137:004172C8 CALL USER32!CallWindowProcA 0137:004172CD MOV [ESI+0C],EAX 0137:004172D0 JMP 004172DB 0137:004172D2 MOV EDX,ESI 0137:004172D4 MOV EAX,EBX 0137:004172D6 CALL 004172DB ==> 004172DB POP EBP 0137:004172DC POP EDI 0137:004172DD POP ESI 0137:004172DE POP EBX 0137:004172DF RET

If you step through this routine, looking for a compare and a jump, you can find the place where the user name you entered is stored. This isn't where we want to be either. We want to be in the routine where our serial number is stored. So... step ALL the way through the code again using F10 until you see the string 'PSDIAL!CODE" on the line again.

Now we're in the serial number routine. Slowly step through the code using F10, until we get to the compare and jump. You should be here:

0137:00480C4D CALL 004151E4 0137:00480C52 MOV EAX,[EBP-08] :user name you entered 0137:00480C55 POP EDX :serial number you entered 0137:00480C56 CALL 00437484 :call the function to compare serial numbers 0137:00480C5B TEST AL,AL :compare serial numbers 0137:00480C5D JZ 00480C94 :jump to unregistered if 0 (0=bad flag) 0137:00480C5F MOV BYTE PTR [EBX+000001C4],01 :otherwise, get a 1 for registered (1=good flag) 0137:00480C66 LEA EDX,[EBP-04] 0137:00480C69 MOV EAX,[EBX+000001C0] 0137:00480C6F CALL 004151E4 0137:00480C74 MOV EAX,[EBP-04]

From my comments above, you should be able to find your correct serial number. If not, you need to press F10 until the line "0137:00480C5B TEST AL,AL" is highligted. Then, since your serial number is stored in EDX, display it by typing: d EDX. (you'll need to press ALT+Up Arrow keys a couple times to see your serial).

My serial number was 674482699-214 (Cracked By Volatility [ID] for my user name). Don't be a lamer, use your own serial number.

If time permits, I'll add more to this essay, showing you how to crack by getting a dead-listing and patching with a hex editor.

*** Disclaimer *** This Essay Is For Knowledge Purposes Only. Neither We, Our ISP, Nor Any Persons Mentioned Shall Be Held Liable For Any Damages Improper Usage May Cause To Your Machine. If You Successfully Crack A Program, You Must Delete It Immediately. If You Want To Keep The Program, Please BUY It! Support Shareware, This Is Our Learning Tool! It Is Illegal To Continue To Use Cracked/Patched Software.

why do programmers bother creating long and or complicated serial numbers for their programs when it's usually so easy to simply sniff out the *real* serial code just by following a few lines of code.

Since I cracked this program without using a Dead Listing I won't tell you to go and create one using W32Dasm but if you really want to learn more about this program it might be a good idea to create one all the same..

First things first..

Run up the program then select the 'File' menu then the 'Register..' option.

You should now be in a simple looking Registration Screen.

Fill in your Name/Handle and a fake serial number.

I used:

The Sandman
999999999

Before clicking on the 'Ok' button press 'Ctrl-D' to activate Softice then type: bpx messageboxa. Now press 'x' to leave Softice.

Now you can click on the 'OK' button.

Softice now breaks at the start of the messageboxa system function.

Press the 'F11' key once and click on the 'OK' button to the message saying your serial code was invalid. Softice should break here..

:00423815 68A7E04400              push 0044E0A7 ;Messagebox Title
:0042381A 6842DF4400              push 0044DF42 ;"You've entered invalid.."
:0042381F 53                      push ebx
:00423820 E848550100              Call USER32.MessageBoxA
:00423825 E979010000              jmp 004239A3 ;We return here

What I normally do here is to scroll the Softice Assembly window until I come across the first occurrence of the following assembler instructions which are nearly always very close by:-

Call XXXXXXXX
cmp Register,Register (or test Register,Register)
Conditional Jump

The first set of these instructions I came across I discounted because it was to do with creating a messagebox:-

:004237EB 686CDE4400            push 0044DE6C ;"Thank you for registering"
:004237F0 53                    push ebx
:004237F1 E877550100            Call USER32.MessageBoxA
:004237F6 85F6                  test esi, esi
:004237F8 7430                  je 0042382A

OK, no problem, I now scrolled up a few more lines and Bingo!, I found another classic set of my favorite set of instructions here:-

:004237CF E80C960000            call 0042CDE0 ;Compare serials
                                              ;eax=ffffffff if fail
                                              ;eax=1 if correct
:004237D4 83C408                add esp, 00000008
:004237D7 85C0                  test eax, eax ;serial correct?
:004237D9 7502                  jne 004237DD ;No? then jump

If you have a dead listing close by for this program then you'll see how close all these instructions are to our original Softice breakpoint on messageboxa.

At this point I cleared all of Softice's previous breakpoints by typing: bc *
then I type: bpx 004237cf then x to leave Softice.

Now re-run the registration process again and once again Softice breaks but this time on our newly created breakpoint at: 004237cf

Press the 'F10' key once, yep that's right don't trace into this call, just step over it. Now it's interesting to monitor the state of the pc's registers after you've just skipped over a call because this can reveal quite a lot about what the call has just been doing.

So now type: D ecx and you'll see in Softice's code window the *real* serial number you need to use to register this babe!.

If you type D edx then you'll see your *fake* serial.

Now re-run this program but now use the *real* serial number you've just sniffed out.

Job Done.

The Crack

None required.

If you intend on using this program beyond it's evaluation period then please BUY IT!

Final Notes

Surly this program is not THAT easy to *crack*!, well yes it was, so it's doesn't really matter if the programmer used a 100 digit serial number to register this program with, we can always sniff it out with relative ease.

My thanks and gratitude goes to:-

Fravia+ for providing possibly the greatest source of Reverse Engineering
knowledge on the Web.

+ORC for showing me the light at the end of the tunnel.

Ob Duh

Do I really have to remind you all that by buying and NOT stealing the software you use will ensure that these software houses will be encouraged to producing even *better* software for us to use and enjoy.

Ripping off software through serials and cracks is for lamers..

If your looking for cracks or serial numbers from these pages then your wasting your time, try searching elsewhere on the Web under Warze, Cracks etc.

Essay by: The Sandman
Page Created: 14th August 1998