Subject: Re: [tram] I-D Action: draft-ietf-tram-stunbis-03.txt

From: Brandon Williams <[email-masked]>
Date: Thu, 02 Apr 2015 14:10:16 -0400

I would prefer to see us fix the down bid attack rather than simply call 
it out. I think that it can be reasonably mitigated. I see these two 
options, and I'm sure there are others.

1. In cases where both MI and MI256 are being send, the client sends a 
comprehension optional attribute indicating that it is sending MI256. 
This attribute is covered by MI. The server can detect MITM down bid.

2. In cases where both MI and MI256 are received, the server's response 
includes a comprehension required attribute indicating that it received 
both. This attribute is covered by the MI256 attribute. The client can 
detect MITM down bid.

I think either of these is a reasonable mitigation, and they are lighter 
weight than moving to (D)TLS.

--Brandon

On 03/26/2015 10:48 PM, Marc Petit-Huguenin wrote:
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> Changelog for -03 (before the WG session in Dallas):
>
> o  SCTP prefix is now 0b00000101 instead of 0x11.
> o  Add SCTP at various places it was needed.
> o  Update the hash agility plan to take in account HMAC-SHA-256.
> o  Adds the bid down attack on message-integrity in the security
>     section.
> o  Update RFC 4013 to I-D.ietf-precis-saslprepbis.
> o  Update RFc 5245 to rfc5245bis.
> o  Cleaned the IANA consideration section.
> o  Add sodium-free SHA256 password algorithm.
> o  Add rational for the NONCE magic prefix.
>
> On 03/26/2015 03:06 PM, [email-masked] wrote:
>>
>> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>>   This draft is a work item of the TURN Revised and Modernized Working Group of the IETF.
>>
>>          Title           : Session Traversal Utilities for NAT (STUN)
>>          Authors         : Marc Petit-Huguenin
>>                            Gonzalo Salgueiro
>>                            Jonathan Rosenberg
>>                            Dan Wing
>>                            Rohan Mahy
>>                            Philip Matthews
>> 	Filename        : draft-ietf-tram-stunbis-03.txt
>> 	Pages           : 58
>> 	Date            : 2015-03-26
>>
>> Abstract:
>>     Session Traversal Utilities for NAT (STUN) is a protocol that serves
>>     as a tool for other protocols in dealing with Network Address
>>     Translator (NAT) traversal.  It can be used by an endpoint to
>>     determine the IP address and port allocated to it by a NAT.  It can
>>     also be used to check connectivity between two endpoints, and as a
>>     keep-alive protocol to maintain NAT bindings.  STUN works with many
>>     existing NATs, and does not require any special behavior from them.
>>
>>     STUN is not a NAT traversal solution by itself.  Rather, it is a tool
>>     to be used in the context of a NAT traversal solution.
>>
>>     This document obsoletes RFC 5389.
>>
>>
>> The IETF datatracker status page for this draft is:
>> https://datatracker.ietf.org/doc/draft-ietf-tram-stunbis/
>>
>> There's also a htmlized version available at:
>> http://tools.ietf.org/html/draft-ietf-tram-stunbis-03
>>
>> A diff from the previous version is available at:
>> http://www.ietf.org/rfcdiff?url2=draft-ietf-tram-stunbis-03
>>
>>
>> Please note that it may take a couple of minutes from the time of submission
>> until the htmlized version and diff are available at tools.ietf.org.
>>
>> Internet-Drafts are also available by anonymous FTP at:
>> ftp://ftp.ietf.org/internet-drafts/
>>
>> _______________________________________________
>> tram mailing list
>> [email-masked]
>> https://www.ietf.org/mailman/listinfo/tram
>>
>
>
> - --
> Marc Petit-Huguenin
> Email: [email-masked]
> Blog: http://blog.marc.petit-huguenin.org
> Profile: http://www.linkedin.com/in/petithug
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-- 
Brandon Williams; Senior Principal Software Engineer
Emerging Products Engineering; Akamai Technologies Inc.