W3C home > Mailing lists > Public > ietf-http-wg@w3.org > October to December 2010

Re: [hybi] workability (or otherwise) of HTTP upgrade

From: Adam Barth <ietf@adambarth.com>
Date: Mon, 6 Dec 2010 16:59:33 -0800
Message-ID: <AANLkTi=+EmQXdm8+7wr9QmF=TXpW=UVuwyVc12JtxewN@mail.gmail.com>
To: Mark Nottingham <mnot@mnot.net>
Cc: Maciej Stachowiak <mjs@apple.com>, hybi <hybi@ietf.org>, HTTP Working Group <ietf-http-wg@w3.org>
On Mon, Dec 6, 2010 at 3:55 PM, Mark Nottingham <mnot@mnot.net> wrote:
> Thanks; will have a read.
> Adam -- nice title, not a loaded question at all ;)

That title is optimized to be evocative for the program committee.  We
considered toning it down for you all.  :)


> On 07/12/2010, at 10:27 AM, Maciej Stachowiak wrote:
>> Adam posted his paper to the hybi list a few days ago, it is available here:
>> http://www.adambarth.com/experimental/websocket.pdf
>> I'd like to see more detail on the data than is found in the paper, but it seems to show a real-world hazard with use of Upgrade, since many intermediaries do not understand it and at least a few are confused into treating subsequent traffic as additional HTTP requests and responses.
>> - Maciej
>> On Dec 6, 2010, at 3:17 PM, Mark Nottingham wrote:
>>> Adam --
>>> It seems to me we can't really make any progress until we see that the assertion in your first sentence is true; it's certainly possible to construct an insecure use of Upgrade, but that doesn't prove that it's impossible to use it securely.
>>> Any chance of getting that report?
>>> Regards,
>>> On 26/11/2010, at 5:54 PM, Adam Barth wrote:
>>>> Using Upgrade for WebSockets is insecure in practice.  My colleagues
>>>> and I have run an experiment using live traffic on the Internet and
>>>> have successfully exploited a number of users using an Upgrade-based
>>>> handshake (our exploit is harmless by proves the concept).  I'm still
>>>> getting clearance from some affected vendors before releasing a report
>>>> on the experiment publicly.  It's looking like I'll be able to release
>>>> the report within a week.
>>>> Upgrade might well be useful for other purposes, and I think
>>>> definition in HTTP is fine.  The problem is that not everyone
>>>> implements Upgrade properly, which leaves room for an attack to
>>>> leverage an Upgrade-based WebSockets handshake in attacks.
>>>> Kind regards,
>>>> Adam
>>>> On Thu, Nov 25, 2010 at 9:06 PM, Greg Wilkins <gregw@webtide.com> wrote:
>>>>> I'm cross posting this message to both the hybi (websockets) and
>>>>> http-bis mailing list as I think this is an issue that is very
>>>>> relevant to both groups.
>>>>> The hybi/websocket protocol, as currently proposed, has a handshake
>>>>> mechanism that is roughly based on the HTTP upgrade mechanism.
>>>>> Progress in the hybi/websocket mailing has ground to a halt because we
>>>>> appear unable to get a clear consensus between the two advocated ways
>>>>> forward:
>>>>> 1) Make the "roughly based" HTTP upgrade mechanism a fully compliant
>>>>> HTTP upgrade.
>>>>> 2) Move away from HTTP upgrade and use another mechanism (potentially
>>>>> CONNECT or SSL extensions)
>>>>> To paraphrase the arguments against 1), there are some that are
>>>>> concerned that an Upgrade based handshake will never be able to be
>>>>> adequately secured against cross protocol attacks from ws-browsers to
>>>>> non ws-servers. Also there is some concern that intermediaries might
>>>>> not well support Upgrade and that other mechanisms might have a higher
>>>>> success rate.
>>>>> So I thought that it would be good to move that discussion from hybi
>>>>> to HTTP-bis so we can stall progress here.... no I mean so that we can
>>>>> get a wider view on the capabilities and vulnerabilities that might
>>>>> apply to Upgrade.
>>>>> My understanding is that Upgrade was included in HTTP for precisely
>>>>> the reason that Websocket wishes to use it - ie to take an existing
>>>>> HTTP connection and to upgrade the protocol run over the connection to
>>>>> something with different capabilities than HTTP.
>>>>> I would also expect that if there are problems with lack of Upgrade
>>>>> support in intermediaries, then it would be easier to get
>>>>> intermediaries to be updated to a standard generic HTTP mechanism
>>>>> rather than some special purpose usage of CONNECT.
>>>>> If websocket is unable to securely use Upgrade, then there must be
>>>>> some fundamental flaw in Upgrade that should either be fixed in
>>>>> httpbis (if allowed by the charter).   If Upgrade cannot be fixed,
>>>>> then perhaps httpbis needs to somehow deprecate the mechanism and we
>>>>> can look together for alternatives?
>>>>> So I'd ask the httpbis readers, are there any reasons you know of that
>>>>> would prevent Upgrade being used for websocket?
>>>>> And I'd ask the hybi upgrade sceptics if they could perhaps voice
>>>>> their concerns about Upgrade in more detail than my paraphrasing
>>>>> above.
>>>>> regards
>>>>> _______________________________________________
>>>>> hybi mailing list
>>>>> hybi@ietf.org
>>>>> https://www.ietf.org/mailman/listinfo/hybi
>>> --
>>> Mark Nottingham   http://www.mnot.net/
>>> _______________________________________________
>>> hybi mailing list
>>> hybi@ietf.org
>>> https://www.ietf.org/mailman/listinfo/hybi
> --
> Mark Nottingham   http://www.mnot.net/
Received on Tuesday, 7 December 2010 01:00:38 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 1 March 2016 11:10:55 UTC