[secdir] sectdir review of draft-ietf-isis-node-admin-tag-08

[Catherine Meadows <[e-mail]>]

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 draft describes an extension to the IS-IS routing protocol, that allows tagging and grouping of nodes
in an IS-IS domain.  This makes it possible to increase the efficiency of route and path selection, since the tags
give information about a router’s capabilities.

The Security Considerations section correctly identifies one of the main security risks of using such tags:  they may leak
sensitive information about, e.g., geographical location.   However, I’m confused by the statement following that:

“This document does not introduce any new security concerns.  Security concerns for IS-IS are already addressed in
[ISO10589], [RFC5304], and [RFC5310] are are applicable to the mechanisms described in this document.”

As far as I can tell, this document *does* introduce new security concerns, because the tags may reveal sensitive
information that may not have been made available otherwise.  Moreover, RFCs 5304 and 5310 concern authentication, not
secrecy, and so do not address information leakage at all.  My own suggestion
for a recommendation would be that implementors should weigh the benefits of putting certain kinds of information on tags
versus the risk of its being used by an attacker, and make their decisions accordingly.  This would not be a SHOULD a MUST
recommendation by the way, but simply advisory.

I’m not sure what is meant by the last sentence in this paragraph:

 Extended authentication mechanisms described in [RFC5304] or [RFC5310] SHOULD be used in
   deployments where attackers have access to the physical networks and
   nodes included in the IS-IS domain are vulnerable.

Is this addressing the problem of sensitive information on tags?  If so, you need to say how.   If it is addressing
spoofing of tags, it should be given its own paragraph, and the threat you are talking about should be made clear.

In the last paragraph, on the misattribution of tags from different domains, what would you recommend for mitigating against
this problem?  Also, since this is in the security considerations section, you should say something about how an attacker
could take advantage of it.  

In my opinion, the Security Considerations section needs a major revision.  However,
I consider this document Almost Ready, because the purpose of the revision would be mainly to make the section more clear, not to address
any overlooked security problems.




Catherine Meadows
Naval Research Laboratory
Code 5543
4555 Overlook Ave., S.W.
Washington DC, 20375
phone: [phone]
fax: [phone]
email: [e-mail] <mailto:[e-mail]>