Re: [secdir] Review of draft-ietf-sfc-architecture-08

["Joel M. Halpern" <[e-mail]>]

While the paragraph you suggest looks reasonable, I am somewhat 
concerned if readers draw the conclusion that we expect to include data 
plane authentication and / or encryption mechanisms as a mandatory part 
of the solution.  There is no such expectation.  While there is reason 
to be concerned about exposure of information across the Internet, the 
document begins by specifically noting that this architecture is for use 
with a single administrative domain.

I am thus concerned that adding the suggested text may give rise to 
unreasonable expectations on solutions which comply with this architecture.

Yours,
Joel

On 5/24/15 3:10 PM, Simon Josefsson wrote:
> Hello.
>
> I have reviewed this document as part of the security directorate's
> ongoing effort to review all IETF documents being processed by the
> IESG.  These comments were written primarily for the benefit of the
> security area directors.  Document editors and WG chairs should treat
> these comments just like any other last call comments.
>
> This is an architectural document, so it doesn't have the usual
> security impact that you can easily review.  The Security
> Considerations section gently refer any security considerations to
> the future documents that will actually realize the archicture.
>
> The security considerations that you would expect to be discussed in an
> architecural document are those on an architectural level.  The
> archicture proposed here is to change how network services are
> delivered.  The document doesn't give many examples, but my
> understanding is that the intended services would include firewalls,
> NAT, proxies, packet filtering, anti-spam measures, anti-DDOS measure,
> QoS, and so on.
>
> The traditional model is static services coupled to network topology
> and physical resource. The new model introduced by this document, as
> far as I understand, is a dynamic model where delivery of these services
> can be moved around more dynamically, by tunneling traffic to the
> service and back.
>
> I may have missed it, but I feel that the security consequences of
> moving to this new architecture is not discussed in the document.
>
> Some obvious security considerations that are introduced with an
> architecture like this are:
>
>    1) When delivery of a service is moved from an on-network-path
>    machine to a machine sitting somewhere else, there ought to be some
>    consideration to authenticating the involved entities and encrypting
>    the traffic between them.
>
>    2) Auditing who has powers over a communication channel will be
>    different -- before you evaluated the wires and who had access to the
>    machines connected to the wires.  Now you have to review the policies
>    configured in the machines and what external entities are involved,
>    together with the operational aspects of this boxes that perform the
>    service delivery.
>
>    3) Moving traffic around raises the challenge how to achieve that
>    without negatively affecting privacy of the traffic.
>
>    4) Protecting the SFC configuration and policies is critical for
>    secure operations.  Anyone who gains access may be able to modify
>    traffic.
>
> If the above is a bit handwavy, allow me to be more concrete.  Adding
> something like the following to the security considerations would at
> least acknowledge that there are inherent security considerations with
> this architecture:
>
>    The architecture described here is different from the current model,
>    and moving to the new model will lead to different security
>    arrangements and modeling. For example, when service functions are
>    moved from on-path static machines to dynamic remote machines, this
>    introduce security and privacy aspects that needs to be addressed.
>
> All this said, I still would classify this document as Ready.  It
> mostly just disappoint me that a new architecture can be introduced
> without containing a significant discussion of security properties.
>
> /Simon
>