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Re: Adding Security Considerations regarding interception to p1

From: Mike Belshe <mike@belshe.com>
Date: Thu, 19 Sep 2013 00:00:28 -0700
Message-ID: <CABaLYCsc6eLv7y=25SUrqnUdiVka3VBxqfy8T2n2OFntR-qp0Q@mail.gmail.com>
To: Willy Tarreau <w@1wt.eu>
Cc: Stephen Farrell <stephen.farrell@cs.tcd.ie>, "Roy T. Fielding" <fielding@gbiv.com>, Mark Nottingham <mnot@mnot.net>, IETF HTTP WG <ietf-http-wg@w3.org>
Mark -

I was about to write that I didn't like your proposal :-(

But after reading Willy's argument, maybe I see a route where it can be
useful.  Specifically, Willy's retort is the common one - discussing "dumb
administrators" and that TLS is not a panacea.  This argument doesn't
appeal to me because any of us can craft a reasonable story about the
clueless guy to support our own point of view.  And the clueless guys don't
read protocol specs anyway :-)

But we don't need to talk about the clueless guy, because even smart
administrators that do read these specs don't always know when to encrypt.
 This could be demonstrated with an example.  Appending to your own text:

Common use of HTTP often contains a considerable amount of sensitive data;
this might include cookies [RFC6265], application data, and even patterns
of access.

When used without encryption, HTTP makes this data vulnerable to passive
interception. There are known instances when third parties have exploited
the in-the-clear nature of "http://" URIs to obtain sensitive information,
for a variety of purposes. Use of TLS [RFC2818] can help to mitigate such
passive interception attacks. Note that TLS itself has many modes of use
with different security properties, and there are currently known attacks
against server authentication in "https://" URIs.

*Content providers should be aware that while content may be public
information, and seemingly not "sensitive", a consumer being observed
accessing that information may still be sensitive.  For example:  suppose
an encyclopedia content provider has a public page on sexually transmitted
diseases.  There is nothing confidential or private in that page.  A
medical student may access that page as research, and not care whether it
is publicly known that they viewed that page.  However, a patient may be
accessing that page because they are researching a sensitive issue.  This
user, unlike either the content provider or the medical researcher,
benefits from additional privacy when the content is deployed via HTTP/TLS
rather than with HTTP alone.*

I dunno - I'm still not in love with this - words without teeth are very
close to pontificating, and I'd rather hold out for a protocol that
actually walks the talk...  Can we do that instead? :-)


On Wed, Sep 18, 2013 at 10:53 PM, Willy Tarreau <w@1wt.eu> wrote:

> On Thu, Sep 19, 2013 at 02:55:00AM +0100, Stephen Farrell wrote:
> > "Properly used, TLS provides good confidentiality
> The problem is precisely here. The mechanism is too complex for the
> casual web admin to deploy it correctly and to understand the
> implications of his choices. Not to mention the client side which
> is generally worse as soon as it's not a browser. TLS is only safe
> iff properly used and very few people know how to use it properly.
> Thus they deploy and feel safe, so they have nothing else to care
> about.
> The only really safe implementations I have seen were in clear text.
> Why ? Simply because their authors knew that a TLS deployment would
> eventually be degraded by clueless admins so they considered that
> they needed to have something robust even when TLS was broken. As
> a result they did all the job in the application (encrypting/signing
> sensible data, timestamping/signing HTTP headers) and the transport
> was as safe as a good TLS deployment without the risk that the
> transport would be degraded further.
> That's why I don't like promoting it as the easiest path to
> confidentiality.
> It's only one element but we tend too often to spread the word that it's
> sufficient, which is totally wrong and counter-productive.
> Willy
Received on Thursday, 19 September 2013 07:00:58 UTC

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