Return-Path: X-Original-To: secdir@ietfa.amsl.com Delivered-To: secdir@ietfa.amsl.com Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id DCA901A000E for ; Sat, 25 Jan 2014 10:09:16 -0800 (PST) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -1.999 X-Spam-Level: X-Spam-Status: No, score=-1.999 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, SPF_PASS=-0.001] autolearn=ham Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HRJ5QoSklh1r for ; Sat, 25 Jan 2014 10:09:13 -0800 (PST) Received: from mail-pb0-x233.google.com (mail-pb0-x233.google.com [IPv6:2607:f8b0:400e:c01::233]) by ietfa.amsl.com (Postfix) with ESMTP id 2B2101A0007 for ; Sat, 25 Jan 2014 10:09:13 -0800 (PST) Received: by mail-pb0-f51.google.com with SMTP id un15so4423739pbc.38 for ; Sat, 25 Jan 2014 10:09:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=a3Fz1aV2tI8yAbuL3G74WvvmCnMhvLeOT0XJHVxDPqA=; b=rO3yae1LOLh/34p4b7M/dIP0c7PTlfoydmTxW4oMForaZPHR80H6ERwyrMRMApBDeA wyAz8A9D/uO8WCHR+hyroBCIGRLB4ZL1rtIP9sD7qEgvnHOhqw8rbP6GjkfCzKe7wkqa KPNCmNGci0irpRI7sgx3+ix8z7sflODJ4xxLmzQw9Qttzj+K+c0PSC9810BYJ5W7AHWg oaBXHhlkJrWdjdaUaigYhiIUDabzAUuLWWZYAFZMZuSiisw8F7GVvwuBrnPiobHLKe9P UOzy4bifgsQp+8JOVgg7A0d5m0gJENVI2Puyn0c9w2ooXpfHuJo1UsE/gfSslhdlVfgN K77Q== MIME-Version: 1.0 X-Received: by 10.68.178.229 with SMTP id db5mr20791955pbc.97.1390673351666; Sat, 25 Jan 2014 10:09:11 -0800 (PST) Received: by 10.68.168.132 with HTTP; Sat, 25 Jan 2014 10:09:11 -0800 (PST) In-Reply-To: <1390663083.06483927@apps.rackspace.com> References: <1369961279.70598635@apps.rackspace.com> <1390663083.06483927@apps.rackspace.com> Date: Sat, 25 Jan 2014 12:09:11 -0600 Message-ID: From: Alan Johnston To: "Scott G. Kelly" Content-Type: multipart/alternative; boundary=047d7b6d8d9620056d04f0cf5fa4 Cc: draft-ietf-cuss-sip-uui.all@tools.ietf.org, "secdir@ietf.org" Subject: Re: [secdir] secdir review of draft-ietf-cuss-sip-uui-10 X-BeenThere: secdir@ietf.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Security Area Directorate List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 25 Jan 2014 18:09:17 -0000 --047d7b6d8d9620056d04f0cf5fa4 Content-Type: text/plain; charset=ISO-8859-1 Scott, Thanks for reviewing the draft again. We will fix that mistake. - Alan - On Sat, Jan 25, 2014 at 9:18 AM, Scott G. Kelly wrote: > Hi Alan, > > It appears that the modifications answer the questions I raised, but I > again want to emphasize my lack of experience with SIP. One nit with the > second paragraph of the security considerations section - it says > > One model treats the SIP layer as untrusted and requires end-to-end > integrity protection and/or encryption. This model can be achieved > by providing these security services at a layer above SIP. In this > case, applications are encouraged to use their own integrity > mechanisms such as encrypting the UUI data before passing it to the > SIP layer. > > Encryption is not an integrity mechanism. One way to fix this would be to > change that last sentence to something like > > In this case, applications are encouraged to use their own integrity > and/or encryption mechanisms. > > Thanks, > > Scott > > On Thursday, January 23, 2014 11:44am, "Alan Johnston" < > alan.b.johnston@gmail.com> said: > > > Scott, > > > > Thanks for your review of the draft. We made some edits based on your > > comments a while back, so I'm pinging you to make sure they address your > > concerns. > > > > http://tools.ietf.org/html/draft-ietf-cuss-sip-uui > > > > Thanks! > > - Alan - > > > > > > On Thu, May 30, 2013 at 7:47 PM, Scott G. Kelly >wrote: > > > >> 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. > >> > >> I have no expertise in SIP, and am providing this review as a > first-level > >> filter for our over-worked security ADs. So, please take my comments > >> accordingly. Also, this review is a day late -- I hope it is still > useful. > >> > >> This document defines a method for exchanging a blob of information > >> between user agents during SIP session establishment (User to User > >> Information, or UUI data) by adding a new SIP header. The data is > intended > >> to be opaque to SIP. > >> > >> There is a related problem statement RFC (6567) that briefly describes 3 > >> different approaches to security, but neither document describes likely > >> threats. They are implicit in the 3 models described in 6567 (e.g. treat > >> the sip layer as "untrusted", treat the sip layer as "trusted", treat > the > >> transport domain as "trusted"), but I found myself wishing I had more > info > >> about real-world threats and countermeasures. > >> > >> Given that I am not a SIP expert (and don't have time to become one as > >> part of this review), I don't know if this is an issue or not, but this > is > >> an impression I think worth mentioning. > >> > >> A second question relates to the binding of the UUI to its originator. > The > >> security considerations section suggests that the UUI might carry > sensitive > >> info requiring privacy or integrity protection, but does not mention > origin > >> authentication. There is a hint in the next paragraph (it says > >> "History-Info can be used to determine the identity of the inserter"), > but > >> the relative security of this mechanism is not clear to me. Could an > >> attacker forge History-Info? I don't know. What are the consequences of > >> such behavior? I don't know. Seems like a well-written security > >> considerations section would lay these questions to rest. > >> > >> Again, I have almost zero knowledge of SIP, so maybe answers are obvious > >> to someone steeped in SIP lore, and I apologize if this is the case. > But, > >> these are my impressions. > >> > >> --Scott > >> > >> > >> > > > > > --047d7b6d8d9620056d04f0cf5fa4 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Scott,

Thanks for reviewing the draft a= gain. =A0We will fix that mistake.

- Alan -
<= /div>


On Sat, = Jan 25, 2014 at 9:18 AM, Scott G. Kelly <scott@hyperthought.com&g= t; wrote:
Hi Alan,

It appears that the modifications answer the questions I raised, but I agai= n want to emphasize my lack of experience with SIP. One nit with the second= paragraph of the security considerations section - it says

=A0 =A0One model treats the SIP layer as untrusted and requires end-to-end<= br> =A0 =A0integrity protection and/or encryption. =A0This model can be achieve= d
=A0 =A0by providing these security services at a layer above SIP. =A0In thi= s
=A0 =A0case, applications are encouraged to use their own integrity
=A0 =A0mechanisms such as encrypting the UUI data before passing it to the<= br> =A0 =A0SIP layer.

Encryption is not an integrity mechanism. One way to fix this would be to c= hange that last sentence to something like

=A0 =A0In this case, applications are encouraged to use their own integrity=
=A0 =A0and/or encryption mechanisms.

Thanks,

Scott

On Thursday, January 23, 2014 11:44am, "Alan Johnston" <alan.b.johnston@gmail.com> sa= id:

> Scott,
>
> Thanks for your review of the draft. =A0We made some edits based on yo= ur
> comments a while back, so I'm pinging you to make sure they addres= s your
> concerns.
>
> =A0 =A0 =A0http://tools.ietf.org/html/draft-ietf-cuss-sip-uui
>
> Thanks!
> - Alan -
>
>
> On Thu, May 30, 2013 at 7:47 PM, Scott G. Kelly <scott@hyperthought.com>wrote:
>
>> I have reviewed this document as part of the security directorate&= #39;s
>> ongoing effort to review all IETF documents being processed by the= IESG.
>> =A0These comments were written primarily for the benefit of the se= curity area
>> directors. =A0Document editors and WG chairs should treat these co= mments just
>> like any other last call comments.
>>
>> I have no expertise in SIP, and am providing this review as a firs= t-level
>> filter for our over-worked security ADs. So, please take my commen= ts
>> accordingly. Also, this review is a day late -- I hope it is still= useful.
>>
>> This document defines a method for exchanging a blob of informatio= n
>> between user agents during SIP session establishment (User to User=
>> Information, or UUI data) by adding a new SIP header. The data is = intended
>> to be opaque to SIP.
>>
>> There is a related problem statement RFC (6567) that briefly descr= ibes 3
>> different approaches to security, but neither document describes l= ikely
>> threats. They are implicit in the 3 models described in 6567 (e.g.= treat
>> the sip layer as "untrusted", treat the sip layer as &qu= ot;trusted", treat the
>> transport domain as "trusted"), but I found myself wishi= ng I had more info
>> about real-world threats and countermeasures.
>>
>> Given that I am not a SIP expert (and don't have time to becom= e one as
>> part of this review), I don't know if this is an issue or not,= but this is
>> an impression I think worth mentioning.
>>
>> A second question relates to the binding of the UUI to its origina= tor. The
>> security considerations section suggests that the UUI might carry = sensitive
>> info requiring privacy or integrity protection, but does not menti= on origin
>> authentication. There is a hint in the next paragraph (it says
>> "History-Info can be used to determine the identity of the in= serter"), but
>> the relative security of this mechanism is not clear to me. Could = an
>> attacker forge History-Info? I don't know. What are the conseq= uences of
>> such behavior? I don't know. Seems like a well-written securit= y
>> considerations section would lay these questions to rest.
>>
>> Again, I have almost zero knowledge of SIP, so maybe answers are o= bvious
>> to someone steeped in SIP lore, and I apologize if this is the cas= e. But,
>> these are my impressions.
>>
>> --Scott
>>
>>
>>
>



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