Cracking Projects For Newbies

Re: Project 6 Task 2
Thursday, 04-Feb-99 16:04:40
    206.248.47.179 writes:

    Task #2

    Checking the dead-listing in W32Dasm we see in the string Ref. There is a string
    String Resource ID=61245: "Thank you for registering %s."
    So double clicking on the string we find ourselves here 40B7C8 which is the good guy string. Clicking the string reference again we see this is the only reference.
    Moving up in the listing the first jmp we find is jne 0040B9BC Lets put our cursor on that line and push the right arrow key and see where it jumps.
    Aha. Jumps to bad guy message String Resource ID=61244: "Sorry, the registration code does not match! Try again or Ca"
    (just above 0040B9BC we find test eax,eax) so to be registered we now know the program needs to have eax = 0 here otherwise we will be unregistered. (This is not important now but may be later.)

    Ok. If we change this NOP, or Jz we should be registered.
    To make sure we could double click the string String Resource ID=61244: "Sorry, the registration code does not match! Try again or Ca" and we find only one reference to this one. ( Double click on the reference in the Str. Ref. Window and see if the code offset changes)

    Looking further above the location 40B9BC there does not seem to be anything else at this point.
    So from this we may deduce only one patch is needed (perhaps we are wrong but from here that is what it seem)
    Actually something more is needed. If we patch this jump with NOP's we are able to register the program with any name and no registration code and receive the thank you message but if we go to the options menu we are not able to get the extra game cards or two player game.
    So more is needed.

    What problems may we encounter if we patched it?
    Looking again at the string reference we see
    String Resource ID=61249: "The program has been modified!"
    Perhaps there is CRC checking of the code to make cracking more difficult or it could just be a scare tactic. (Playing around altering the code I was unable to have the program display the message.)

    There is one small safeguard to prevent patching is that the program is read only.
    On the .exe right click the mouse and go to properties then uncheck the read-only box. Now we can alter the program.

    Princess







    Princess


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Princess: Princess' tread Project 6 (03-Feb-99 18:51:42)

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