OSEC

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Valdis.Kletnieks_at_vt.edu
Date: Tue Nov 05 2002 - 23:16:33 CST

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    On Tue, 05 Nov 2002 22:38:32 +0100, Florian Weimer <WeimerCERT.Uni-Stuttgart.DE> said:

    > What about HTTP headers which advise user agents to disable some
    > features, e.g. read/write access to the document or parts of it via
    > scripting or other Internet Explorer interfaces?
    >
    > Is anybody interested in writing an Informational RFC on this topic?

    Pointless.

    It's one thing for a web browser to refuse to do something because it suspects
    that it has been asked something underhanded (for instance, to not give a
    cookie value to a script if it were tagged 'httponly').

    It's something else for a server to try to restrict user agents that way.
    A well-behaved user agent won't need the hints, and a malicious one won't
    listen to them....

    (Note - I'm talking here about a server trying to say "Thou Shalt Not Do
    XYZ" and expecting to be listened to - if anything, this is a big clue to
    the attacker that they should look for a way to try to do XYZ anyhow. That
    never works. On the other hand, there are *lots* of areas where *HINTS*
    (like the HTTP 'Expires' header) are quite valuable...

    Remember - we've seen enough Bugtraq postings about people who try to use
    hidden fields in an HTML document for security, and get it wrong...

    -- 
    				Valdis Kletnieks
    				Computer Systems Senior Engineer
    				Virginia Tech
    

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