Re: Hotmail security vulnerability - injecting JavaScript using

From: Olaf Titz (olafat_private)
Date: Tue Sep 14 1999 - 00:57:25 PDT

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    In article <37DCF0FE.908E4B4Fat_private> you write:
    > Note: This is not a browser problem, it is Hotmail's problem.
    
    It is a browser problem, at least for the Netscape version.
    
    > <P STYLE="left:expression(eval('alert(\'JavaScript is
    > executed\');window.close()'))" >
    
    One could argue that styles can be computed via Javascript...
    
    > <STYLE TYPE="text/javascript">
    
    ...but that is ridiculous. The browser should simply ignore a
    stylesheet of an unknown type, there is a reason for the type
    parameter after all. (Unless it is a deliberate feature that you can
    substitute STYLE for SCRIPT, which I somehow doubt.)
    
    This is not only a problem for Hotmail but for all sorts of proxies
    which filter Javascript for security reasons. Since there is at least
    one recent version of both NC and IE which _doesn't_ let you disable
    Javascript at all due to bugs, such filtering is an absolute
    necessity, but you need to know where in the data stream it can
    appear.
    
    Btw. the example given for IE is a classic example of what is so wrong
    with Javascript: you can do anything with it - including e.g. trivial
    stealing of passwords by popping up fake login dialogs - _even if it
    doesn't make sense in the context_. This alone is a reason to
    completely block and disable it.
    
    Olaf
    



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