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Re: [#95] Multiple Content-Lengths

From: Eric J. Bowman <eric@bisonsystems.net>
Date: Sun, 17 Oct 2010 23:31:51 -0600
To: Mark Nottingham <mnot@mnot.net>
Cc: Julian Reschke <julian.reschke@gmx.de>, Maciej Stachowiak <mjs@apple.com>, Adam Barth <w3c@adambarth.com>, "William Chan (ι™ˆζ™Ίζ˜Œ)" <willchan@chromium.org>, "Roy T. Fielding" <fielding@gbiv.com>, HTTP Working Group <ietf-http-wg@w3.org>
Message-Id: <20101017233151.2aea8219.eric@bisonsystems.net>
OK, that's definitely a browser vulnerability if the first C-L is used.
But how is this *still* a vulnerability under the current wording?  In
the presence of multiple C-L headers, if length is determined by reading
until connection close, then no splitting occurs.

-Eric

Mark Nottingham wrote:
>
> http://www.securiteam.com/securityreviews/5CP0L0AHPC.html
> 
> Technique #2.
> 
> 
> On 18/10/2010, at 4:00 PM, Eric J. Bowman wrote:
> 
> > Mark Nottingham wrote:
> >> 
> >>> We can't simply break formerly-conforming implementations.
> >> 
> >> We can if it's a security issue.
> >> 
> > 
> > The security issue in question is "HTTP request smuggling" which is
> > an attack vector which always takes the form of a malicious request
> > from a user-agent.  All it is the other way around, is a broken
> > server putting itself at risk.  There's no justification for a MUST
> > even if there is consensus for it.
> > 
> > I thought the consensus the WG was after, was whether or not to
> > discard all but the first C-L or the last C-L.  The current
> > proposed language says read to connection close, instead.  This
> > makes loads of sense to me, instead of MUST fail hard based on what
> > concern, exactly?
> > 
> > -Eric
> 
> --
> Mark Nottingham   http://www.mnot.net/
> 
> 
> 
> 
Received on Monday, 18 October 2010 05:32:28 GMT

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