Re: [Isis-wg] Genart last call review of draft-ietf-isis-auto-conf-04

"Les Ginsberg (ginsberg)" <ginsberg@cisco.com> Fri, 07 April 2017 21:30 UTC

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From: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
To: Robert Sparks <rjsparks@nostrum.com>, "gen-art@ietf.org" <gen-art@ietf.org>
CC: "draft-ietf-isis-auto-conf.all@ietf.org" <draft-ietf-isis-auto-conf.all@ietf.org>, "ietf@ietf.org" <ietf@ietf.org>, "isis-wg@ietf.org" <isis-wg@ietf.org>
Thread-Topic: Genart last call review of draft-ietf-isis-auto-conf-04
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Date: Fri, 7 Apr 2017 21:30:14 +0000
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Subject: Re: [Isis-wg] Genart last call review of draft-ietf-isis-auto-conf-04
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Robert -

> -----Original Message-----
> From: Robert Sparks [mailto:rjsparks@nostrum.com]
> Sent: Friday, April 07, 2017 2:18 PM
> To: Les Ginsberg (ginsberg); gen-art@ietf.org
> Cc: draft-ietf-isis-auto-conf.all@ietf.org; ietf@ietf.org; isis-wg@ietf.org
> Subject: Re: Genart last call review of draft-ietf-isis-auto-conf-04
> 
> 
> 
> On 4/7/17 3:55 PM, Les Ginsberg (ginsberg) wrote:
> > Robert -
> >
> > Thanx for the review.
> > Reply inline.
> >
> >> -----Original Message-----
> >> From: Robert Sparks [mailto:rjsparks@nostrum.com]
> >> Sent: Friday, April 07, 2017 1:25 PM
> >> To: gen-art@ietf.org
> >> Cc: draft-ietf-isis-auto-conf.all@ietf.org; ietf@ietf.org;
> >> isis-wg@ietf.org
> >> Subject: Genart last call review of draft-ietf-isis-auto-conf-04
> >>
> >> Reviewer: Robert Sparks
> >> Review result: Ready with Issues
> >>
> >> I am the assigned Gen-ART reviewer for this draft. The General Area
> >> Review Team (Gen-ART) reviews all IETF documents being processed by
> >> the IESG for the IETF Chair.  Please treat these comments just like
> >> any other last call comments.
> >>
> >> For more information, please see the FAQ at
> >>
> >> <https://trac.ietf.org/trac/gen/wiki/GenArtfaq>.
> >>
> >> Document: draft-ietf-isis-auto-conf-04
> >> Reviewer: Robert Sparks
> >> Review Date: 2017-04-07
> >> IETF LC End Date: 2017-04-10
> >> IESG Telechat date: 2017-04-13
> >>
> >> Summary: Ready for publication as Proposed Standard, but with one
> >> possible thing to add to the security consideration section
> >>
> >> This document is clear and seems straightforward to implement.
> >>
> >> I think, however, there is an attack possibility you should call out
> >> in the security considerations section. As home routers are used as
> >> examples of elements that might use this protocol, consider the case
> >> of a malicious party wanting to deny service in that home.
> >> A suborned device in the home could watch for the protocol, and
> >> present a crafted packet to force the home router(s) to re-start the
> >> autoconfiguration protocol continually (by claiming to be a duplicate
> >> and being careful to make it the routers job to restart).
> >> Having the md5 password configured would mitigate this attack.
> > [Les:] The draft says two things which are relevant:
> >
> > 3.5.1.  Authentication TLV
> >
> >     It is RECOMMENDED that IS-IS routers supporting this specification
> >     offer an option to explicitly configure a single password for HMAC-
> >     MD5 authentication as specified in[RFC5304].
> >
> > 4.  Security Considerations
> >
> >     In general, the use of authentication is incompatible with auto-
> >     configuration as it requires some manual configuration.
> >
> > It seems to me that these sections adequately cover your point.
> > ???
> They provide the mitigation. They do not call out the risk.
> 
> The current security considerations section says for wired networks, plugging
> into the wire is protection enough, and you don't need to use the
> authentication tlv.  I don't think that's true given the possibility of this attack.
> I suggest discussing the attack in the security considerations section and
> pointing to using the Authentication TLV with it's onerous bit of manual
> configuration as the mitigation.
> 
[Les:] If you insist I am OK with this - but frankly you are twisting my arm. :-)
System-id duplication is a problem for any deployment - not just autoconfig deployments. And it will be disruptive in any network until it is resolved.
The only thing autoconfig has added is a way to resolve this w/o manual intervention. This in no way increases the vulnerability nor the disruption the attacker can produce. (Yes - I state that quite intentionally).
So you are asking us to repeat a discussion which has already been held in the context of RFC 5304 and RFC 5310.

It would be more appropriate to add the normal reference to RFC 5304/5310 in the Security section than what you propose.

   Les

> >
> >      Les
> >