Java webstart also allows execution of arbitrary code

From: Jelmer (jelmerat_private)
Date: Wed Jul 17 2002 - 16:41:38 PDT

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    It would seem that I opened up a can of worms when i created my icq +
    msie advisory the other day
    Wich presented a new way to execute arbitrary code on a users machine
    Java webstart is equally vulnerable
    
    Java webstart is a revolutionary way of deploying java applications and
    comes standard with jdk and jre 1.4
    
    
    It opens .jnlp with the mime type application/x-java-jnlp-file automaticly
    and then stores downloaded content to known location on the users harddisk
    namely
    
    C:\Program Files\Java Web
    Start\.javaws\cache\http\D$MYHOSTNAMEHERE$\P80\DMimages
    
    in this case i choose to setup an icon in the jnlp file like this
    
    <icon href="images/jelmer.gif" width="32" height="32" />
    
    it then gets saved as
    
    C:\Program Files\Java Web
    Start\.javaws\cache\http\D$MYHOSTNAMEHERE$\P80\DMimages\RMjelmer.gif
    
    In reallity this file is nothing else then our trusted renamed mht file that
    can be called
    
    example at :
    
    http://kuperus.xs4all.nl/webstart.htm
    
    
    I believe a great number of programs to be vulnerable to this exploit
    and would currently recommend
    going through the filetypes (open windows explorer not internet explorer
    , then goto tools > folder options > file types and disable ALL
    extentions that have their default action set to open. I really can't
    tell how many programs are affected but there seem to be quite a few.
    
    This is really quite a severe vulnerability as basicly anyone with basic
    computer knowlage can exploit this
    



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