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Thread: ecx overwritten +overflow

  1. #1

    ecx overwritten +overflow

    Hello all,
    I kindly ask if someone could explain me in a simple way which are the "right" steps to put the right address into ecx to land inside myjunk.
    This one is my "actual" situation:

    ecx offset is 15000
    myjunk = "A"*15000
    ecxaddress = ?? how can i check which readable address i need to put here?? i' m using immunity debugger

    I noticed that there is another thread below but it is not clear for me (i have the same problem)
    sorry for the noob question!! hope that you can understand
    thanks a lot

  2. #2
    well, first of all it might be an idea to give us an idea of what you are actually doing..

  3. #3
    yes sure, nothing special .. i'm playing with a small custom application and i found a buffer overflow so i'm trying to exploit it just for fun, below there is the stack record:
    the stack:

    eax 00000003
    ecx 42424242
    eip 0048AD90 appl.0048AD90

    Best regards
    Last edited by blowfrank; December 21st, 2010 at 11:15.

  4. #4
    This might not be exploitable since EIP was not overwritten. The debugger stopped because of an access violation, look what instruction the debugger stopped at to see if it is a read or write error. If it's a write error and you can control both the destination and the content this might be exploitable. Also you should try to pass the exception (Shift-F9) to see if the SEH chain is overwritten. You can also try with a shorter/longer buffer.

    Needless to say you will need a basic understanding of assembly to exploit this. If you are just starting with exploit writing you might want to try a simpler one where you directly overwrite EIP.
    I promise that I have read the FAQ and tried to use the Search to answer my question.

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