Re: New Java Security Flaw Found

From: Mikolaj J. Habryn (dichro-7f3e596at_private)
Date: Mon Jul 20 1998 - 23:07:33 PDT

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    >>>>> "SG" == Sean Garagan <garaganat_private> writes:
    
        SG> I was actually quite surprised to see this when I wrote a
        SG> ClassLoader a while ago.  I had wrongly assumed Sun would hard
        SG> code checks for the core Java classes.  It looks like Sun
        SG> relies on proper security implementations to prevent the
        SG> ClassLoader from being replaced.
    
      Forcing java.lang.* to go through the system ClassLoader would be
    somewhat unfortunate in somce cases. There are circumstances
    (specifically in environments where you are handling potentially
    hostile foreign code) where you will want to either totally refuse
    access to some classes (java.lang.reflect leaps to mind), or redefine
    them (make methods final, or potentially remove some methods
    altogether). Yes - you're violating bits of the specification, but
    sometimes information leaks are things you really don't want.
    
      To reiterate, not protecting java.lang.* is *not*, IMHO, a
    bug. ClassLoaders are dangerous things, and you want to be very
    careful about who gets to play with them. And ClassLoader isn't the
    only class worth having a good, long look at. If you're trying to
    maintain the integrity of separate protection domains, all running
    foreign code but interacting in a single VM, then java.lang.Object is
    where you start worrying.
    
    m.
    



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