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Thread: basic assembly question for gurus

  1. #1
    Junior Member
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    Im reading thru "The Art of Exploitation" and had a quick asm question. When you grab or set data in a register like [epb-4] like when you zero it. Are you only setting a subset of the registrar? Is it just to efficiency or do I have this totally wrong.

    naturally right after I post this he covers it and I was completely wrong. Thou im confused why you would want to change the address, i assume that you could overwrite data stored at that address.

  2. #2
    Just burned his ISO Jase21's Avatar
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    Oct 2007
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    You can using different addressing modes. The above one is just one of them.
    ..lost in silence™

  3. #3
    Just burned his ISO
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    Zero it in the sense u mean Xor the registers or memmory location?? well if ur are xor ing [ebx-4] onle tht data in tht location will only get zero

  4. #4
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    If you are messing with calls and the stack, then you need to manually set EBP in your shellcode, otherwise NASM or similar does this for you.

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