Re: [secdir] secdir review of draft-ietf-isis-sbfd-discriminator-02

Tom Yu <> Wed, 18 November 2015 19:28 UTC

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From: Tom Yu <>
To: "Les Ginsberg \(ginsberg\)" <>
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Date: Wed, 18 Nov 2015 14:28:01 -0500
In-Reply-To: <> (Les Ginsberg's message of "Wed, 18 Nov 2015 04:31:53 +0000")
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Subject: Re: [secdir] secdir review of draft-ietf-isis-sbfd-discriminator-02
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Given that S-BFD is still in AD Evaluation, it seems that there is still
an opportunity to update the S-BFD Security Considerations, so that the
IS-IS draft will no longer point to apparently absent text in the S-BFD
Security Considerations.

"Les Ginsberg (ginsberg)" <> writes:

> Tom -
> Thanx for the review.
> If you are not happy with the Security section of the base S-BFD draft it seems to me it makes the most sense to address any issues in that document. Trying to make up for any shortcomings in S-BFD draft by adding to  the IGP drafts (there is a similar OSPF S-BFD draft) when the IGPs are merely acting as a transport for opaque information (as you say) does not seem appropriate to me.
> Can we close on this issue?
>    Les
>> -----Original Message-----
>> From: Tom Yu []
>> Sent: Tuesday, November 17, 2015 7:06 PM
>> To:;; draft-ietf-isis-sbfd-
>> Subject: secdir review of draft-ietf-isis-sbfd-discriminator-02
>> 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.
>> Summary: ready with nits
>> I agree with the first paragraph of the Security Considerations, in that I think
>> it's unlikely that this document introduces security risks for IS-IS, which as I
>> understand it, effectively transports the proposed S-BFD discriminators as an
>> uninterpreted opaque payload.
>> The second paragraph
>>    Advertisement of the S-BFD discriminators does make it possible for
>>    attackers to initiate S-BFD sessions using the advertised
>>    information.  The vulnerabilities this poses and how to mitigate them
>>    are discussed in the Security Considerations section of [S-BFD].
>> refers to the Security Considerations of the [S-BFD] base document.  The [S-
>> BFD] Security Considerations describe some strengthening practices, but
>> doesn't seem to describe the vulnerabilities in significant detail.
>> [S-BFD] Security Considerations seems to describe an attack where someone
>> impersonates the responder, but not one where someone impersonates an
>> initiator.
>> Other sections of [S-BFD] might imply the existence of this sort of
>> vulnerability, but the Security considerations seems not to mention it
>> explicitly.  I'm not sure whether it's best to leave things alone, revise this
>> document, or revise [S-BFD].
>> -Tom