Re: Gzip & segmentation faults

From: David LeBlanc (dleblancat_private)
Date: Thu Dec 25 1997 - 09:31:54 PST

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    >Of course it shouldn't be really dangerous, but I also found
    >Attached example of 'evil' archive (Altered.gz) has been created by
    >compressing empty file with gzip's -n switch. After all, byte at offset
    >0x0a (one of possibilities :) has been changed.
    >Under Linux, attempt of unziping or viewing this file will cause
    >nice segmentation fault.
    
    Under NT, it just throws an exception.  Probably is exploitable if you
    dinked with it enough.  Instruction well in the executable's range
    references memory at 0x1.
    
    >MS-DOS gzip screws-up totally.
    
    Considering that MS-DOS is relatively screwed up to begin with, and has few
    to no redeeming qualities, I don't find this surprising.
    
    Sigh - millions of buffer overruns everywhere, and not enough time to
    exploit them all.
    
    
    David LeBlanc           |Why would you want to have your desktop user,
    dleblancat_private |your mere mortals, messing around with a 32-bit
                            |minicomputer-class computing environment?
                            |Scott McNealy
    



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