RE: TRACE used to increase the dangerous of XSS.

From: Thor Larholm (thorat_private)
Date: Thu Jan 23 2003 - 01:10:49 PST

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    I just finished reading this so-called whitepaper and the press release, and
    all I can say is hyped, sensationalised snakeoil.
    
    The HttpOnly cookie feature, a proprietary Microsoft extension designed to
    mitigate a single aspect of XSS, can be circumvented in myriads of ways. In
    fact, reading the HTTP response in any other way than through the
    document.cookie property immediately exposed through JS will return the
    cookie to you. Calling from JS to a Java applet that in turn parses a HTTP
    response, using a Flash movie (or most any other plugin) or even needlessly
    complicating matters by parsing the BODY of a TRACE response received
    through XMLHTTP - such as this 'whitepaper' suggests.
    
    By design, HttpOnly makes the cookie available only through the HTTP
    headers - which, among many others, the XMLHTTP control can read.
    
    What we end up with from WhiteHat Security is a way to circumvent the
    HttpOnly cookie feature in IE6SP1, nothing else. In itself, worthy of a note
    in a roundup of browser problems or a comment in a reply to the posting
    announcing the HttpOnly feature on Bugtraq - but hardly a whitepaper,
    pressrelease and blurbs such as comparing this to Code Red and Nimda or
    calling this a flaw in all web servers worldwide. This is simply not "a new
    class of web-app-sec attack" or a flaw in TRACE, as hyped by WhiteHat
    Security.
    
    System administrators should most definitely not waste their precious time
    on implementing the silly workarounds suggested, such as disabling
    TRACE/TRACK requests. The one, and only, impact the discovery from WhiteHat
    Security has is that it re-enables cookie reading from JS despite if you had
    already cared to specifically alter your webapplication to accomodate this.
    
    All the boojah and fuss about not requiring an actual XSS in the
    webapplication or being able to impose XSS on arbitrary foreign domains,
    factors that would indeed be a cause of concern, is utterly and completely
    unrelated to the findings of WhiteHat Security. These are mere
    demonstrations of already publicly known unpatched vulnerabilities in
    Internet Explorer ( of which there are currently 19 -
    http://www.pivx.com/larholm/unpatched/  ).
    
    WhiteHat Security paired a minor low-impact notice of their own with
    existing proof-of-concept code from several critical high-impact
    vulnerabilities discovered, and long disclosed, by thirdparty researchers,
    dubbed it their own and wrote up a fancy press release filled with
    inaccuracies announcing a indifferent 'whitepaper' scathered with obscure
    irrelevancies.
    
    In short, snakeoil.
    
    Regards
    Thor Larholm
    PivX Solutions, LLC - Senior Security Researcher
    
    Latest PivX research: Multi-vendor Game Server DDoS Vulnerability
    http://www.pivx.com/press_releases/mk_mk001.html
    
    
    -----Original Message-----
    From: Jeremiah Grossman [mailto:jeremiahat_private]
    Sent: 22. januar 2003 21:33
    To: bugtraqat_private; webappsecat_private;
    vulnwatchat_private
    Subject: TRACE used to increase the dangerous of XSS.
    
    
    WhiteHat Security has released a new white paper discussing a new class
    of web-app-sec attack (XST) which potentially affects all web servers
    supporting TRACE.
    
    The white paper explains all the detailed technical results we have
    found so far. We are fairly certain this particular issue will spark
    much debate and encourage those interested to read and comment.
    
    
    White Paper Mirrors:
    http://www.betanews.com/whitehat/WH-WhitePaper_XST_ebook.pdf
    http://www.cgisecurity.com/whitehat-mirror/WhitePaper_screen.pdf
    http://www.boarder.org/WH-WhitePaper_XST_ebook.pdf
    http://www.forumgalaxy.com/whmirror/WhitePaper_screen.pdf
    
    Press Release
    http://www.whitehatsec.com/press_releases/WH-PR-20030120.txt
    



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