Subject: [secdir] Fwd: RE: SecDir review of draft-williams-websec-session-continue-prob-00

From: Stephen Farrell <[email-masked]>
Date: Wed, 06 Feb 2013 09:44:17 +0000

Hi the websec WG would like to get an early review of this
one as they consider adopting it. Any takers?

Ta,
S

-------- Original Message --------
Subject: RE: SecDir review of draft-williams-websec-session-continue-prob-00
Date: Wed, 6 Feb 2013 08:40:01 +0000
From: Yoav Nir <[email-masked]>
To: Sean P. Turner <[email-masked]>,        Stephen Farrell
<[email-masked]>
CC: Tobias Gondrom <[email-masked]>

Sean?  Stephen?

-----Original Message-----
From: Yoav Nir
Sent: Wednesday, January 30, 2013 7:02 AM
To: Sean P. Turner; Stephen Farrell
Cc: Tobias Gondrom
Subject: SecDir review of draft-williams-websec-session-continue-prob-00

Hi

The subject draft is about creating a session management protocol for
HTTP, that will be (a) more secure than using cookies and (b) tied to
authentication.

This is a proposed work item for the WebSec working group, and is not
(yet) part of our charter.

I think having a security review this early on will help the working
group reach a decision (hopefully in or around Orlando), and may help us
find that we've missed some really important issues and requirements.

Would you be willing to ask SecDir to review this?

Thanks

Yoav

---

From: Ben Laurie <[email-masked]>
Date: Thu, 7 Feb 2013 01:58:27 +0000

> one as they consider adopting it. Any takers?

Not really a proper review, but some thoughts:

" 4. Resistance to active attacks on https. [NOTE: This should

        probably NOT be a requirement.  Instead we should be happy to
        note where a proposed protocol provides this.]"

I'm very confused by this point, but...

a) What active attacks? Need to specify them.

b) If there are active attacks that are actually effective (surely
not?) that can be avoided by these protocols, then avoidance should be
compulsory.

And then...

" 8. Session continuation must provide protection against man-in-the-

        middle (MITM) attacks when using TLS.  (This is important when
        using anonymous Diffie-Hellman cipher suites for TLS, as well as
        when using server certificates from low-value Public Key
        Infrastructures (PKI)."

Seems to be a couple of examples of what they're talking about.

" 10. Must work across all types of proxies. Proxies that can modify

        the plaintext HTTP requests and responses can (but should not)
        interfere with any session continuation protocol."

A man-in-the-middle is a type of proxy, so this seems like an
unsatisfiable requirement.

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---

From: Ben Laurie <[email-masked]>
Date: Thu, 7 Feb 2013 08:10:48 +0000

> unsatisfiable requirement.

Actually, that's not quite right. Protocols can work across a proxy,
but what's required is that the proxy does not gain the ability to
pretend to be one of the endpoints.

If you satisfy this, then a MitM can snoop, but can't masquerade.

But this seems to impose quite a strong constraint on the protocol: in
particular, future traffic must somehow be bound to the (end-to-end)
session continuation.