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Comments on the "new" 2518 -- XSS

From: Kevin Wiggen <kwiggen@xythos.com>
Date: Wed, 1 Mar 2006 18:05:10 -0800
Message-ID: <03E7D3E231BB7B4A915A6581D4296CC602062E14@NSNOVPS00411.nacio.xythos.com>
To: <w3c-dist-auth@w3.org>
Webdav needs to mention (and hopefully help) solve XSS attack problems.
XSS (Cross-Site Scripting) is aimed at inserting active code in an HTML
document to either abuse client-side active scripting holes, or to send
privileged information (e.g. authentication/session cookies) to a
previously unknown evil collection site. 


Webdav to date is content agnostic and allows for clients to retrieve
and save information to/from a server.  Unfortunately with Javascript
and some knowledge of webdav, people can start to "hack" webdav servers
to do unexpected things.  Imagine I upload (using PUT) a HTML page that
uses a browser xmlHTTP() to send a propfind to the server and then issue
DELETE to everything I could find.  By simply sending you a link to a
URL on a common secured server, a browser will ask you to log in and
then execute the javascript AS YOU.  There are a lot of problems that
smart people can create because the GET and other Webdav methods all
originate from the same server.  There are possible solutions (from
scraping all input and not allowing certain content) but each always has
some drawbacks (hey I want that javascript to do something important on
my webpage, you can't cut it out when I upload it).  

A separate but related issue is the MS "translate" issue.  If someone
uploads a jsp to a server, when they request it back, do they want the
server to give the jsp? Or execute the jsp and return the result?  

It seems that Webdav (web distributed AUTHORING and versioning) could
take some steps to help out both of these areas.  One line of thinking
(notice I don't say solution) is to have Webdav separate the authoring
world from the view (or execute world).  In this world there would be
two different namespaces (one for Webdav and one for GET/Execute).  The
webdav world would tell clients that it is meant for authoring and thus
servers will NOT execute things like jsps and clients should NOT render
and execute these objects (like javascript in HTML) in things like
browsers but rather a edit mode (like HTML editor).  In this way,
Javascript should not be executed by HTML Editors and the namespace will
be protected from malicious code stored in the sheep's clothing of HTML.

Again I believe it important for Webdav to speak about these problems
and try to give solutions.
Received on Thursday, 2 March 2006 02:05:13 UTC

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