Re: [Dime] unexpected consequence of deprecating E2E security in RFC 3588 bis

<dieter.jacobsohn@telekom.de> Thu, 27 September 2012 10:01 UTC

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From: <dieter.jacobsohn@telekom.de>
To: <glenzorn@gmail.com>, <lionel.morand@orange.com>, <dime@ietf.org>
Date: Thu, 27 Sep 2012 12:01:35 +0200
Thread-Topic: [Dime] unexpected consequence of deprecating E2E security in RFC 3588 bis
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Cc: draft-ietf-dime-rfc3588bis@tools.ietf.org, Stefan.Schroeder06@telekom.de, turners@ieca.com, stephen.farrell@cs.tcd.ie
Subject: Re: [Dime] unexpected consequence of deprecating E2E security in RFC 3588 bis
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Hello Glen
After discussing it also with some security people I think that the existing text is more accurate and should stay.
The existing text refers to "intermediary is known to be operated as part of the same administrative domain as the endpoints", which is fine. We don't have end-to-end security in 3588bis, true. But 13.3 offers exactly this party1-to-party2 security as almost equivalent to e2e security. 

The new proposed text would allow other alternatives beyond that, based on "locally trusted configuration". But what does that mean in practice? I think such a statement would allow just anything and move away from any tangible technical security.

Best Regards
Dieter Jacobsohn


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-----Ursprüngliche Nachricht-----
Von: dime-bounces@ietf.org [mailto:dime-bounces@ietf.org] Im Auftrag von Glen Zorn
Gesendet: Donnerstag, 27. September 2012 05:58
An: lionel.morand@orange.com
Cc: draft-ietf-dime-rfc3588bis; dime mailing list; turners; Stephen Farrell
Betreff: Re: [Dime] unexpected consequence of deprecating E2E security in RFC 3588 bis

On 09/27/2012 01:26 AM, lionel.morand@orange.com wrote:

Copying the Security ADs.

> Is it somehow covered in
 > http://tools.ietf.org/html/draft-ietf-dime-rfc3588bis-34#section-13.3?
 >
 >
 >
Diameter AVPs often contain security-sensitive data; for example,
> user passwords and location  data, network addresses and
 > cryptographic keys. The Diameter messages containing such AVPs MUST  > only be sent protected via mutually authenticated TLS or IPsec. In  > addition, those messages SHOULD NOT be sent via intermediate nodes  > that would expose the sensitive data at those nodes except in cases  > where an intermediary is known to be operated as part of the same  > administrative domain as the endpoints so that an ability to  > successfully compromise the intermediary would imply a high  > probability of being able to compromise the endpoints as well.
 >
 > Do you think that it is needed to add somewhere that "the originator  > has locally trusted configuration that indicates that end-to-end  > security is not needed"?

I think that something should be done since as it stands the language is weaker in bis than in RFC 3588; the protocol is actually less secure :-(.  I would suggest changing Section 13.3 (quoted above) to say some thing like this:

    Diameter AVPs often contain security-sensitive data; for example,
    user passwords and location data, network addresses and cryptographic
    keys.  The Diameter messages containing such AVPs MUST only be sent
    protected via mutually authenticated TLS or IPsec.  In addition, those
    messages MUST NOT be sent via intermediate nodes unless there is
    end-to-end security between the originator and recipient or the originator has locally
    trusted configuration that indicates that end-to-end security is not needed
    (for example, where an intermediary is known to be operated as part of the
    same administrative domain as the endpoints so that an ability to
    successfully compromise the intermediary would imply a high
    probability of being able to compromise the endpoints as well). 
Note, however, that
    no end-to-end security mechanism is specified in this document.

However, I don't really want to delay publication any more than I already have ;-), so if that change would trigger a whole new IESG review (or worse, another IETF LC) I would rather handle it in an erratum later.

>
 >
 > Lionel
 >
 >
 > -----Message d'origine----- De : dime-bounces@ietf.org
 > [mailto:dime-bounces@ietf.org] De la part de Glen Zorn Envoyé :
 > mercredi 26 septembre 2012 12:47 À : draft-ietf-dime-rfc3588bis Cc :
 > dime mailing list Objet : [Dime] unexpected consequence of
 > deprecating E2E security in RFC 3588 bis
 >
 > Section 4.5 of RFC 3588 says: The following table describes the
 > Diameter AVPs defined in the base protocol, their AVP Code values,
 > types, possible flag values and whether the AVP MAY be encrypted.
 > For the originator of a Diameter message, "Encr" (Encryption) means
 > that if a message containing that AVP is to be sent via a Diameter
 > agent (proxy, redirect or relay) then the message MUST NOT be sent
 > unless there is end-to-end security between the originator and the
 > recipient and integrity / confidentiality protection is offered for
 > this AVP OR the originator has locally trusted configuration that
 > indicates that end-to-end security is not needed. Similarly, for the
 > originator of a Diameter message, a "P" in the "MAY" column means
 > that if a message containing that AVP is to be sent via a Diameter
 > agent (proxy, redirect or relay) then the message MUST NOT be sent
 > unless there is end-to-end security between the originator and the
 > recipient or the originator has locally trusted configuration that
 > indicates that end-to-end security is not needed.
 >
 > The corresponding section of 3588bis says: The following table
 > describes the Diameter AVPs defined in the base protocol, their AVP
 > Code values, types, and possible flag values.
 >
 > Considerable information (and normative guidance) seems to have been
 > lost here: in particular, the statements that "the message MUST NOT
 > be sent unless... the originator has locally trusted configuration
 > that indicates that end-to-end security is not needed" would seem to
 > be valid even in the absence of an E2E security solution.
 > _______________________________________________ DiME mailing list
 > DiME@ietf.org https://www.ietf.org/mailman/listinfo/dime
 >
 > 
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