Re: [conex] Stephen Farrell's No Objection on draft-ietf-conex-destopt-09: (with COMMENT)

Stephen Farrell <stephen.farrell@cs.tcd.ie> Fri, 09 October 2015 11:04 UTC

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To: =?UTF-8?Q?Mirja_K=c3=bchlewind?= <mirja.kuehlewind@tik.ee.ethz.ch>, Bob Briscoe <ietf@bobbriscoe.net>, Suresh Krishnan <suresh.krishnan@ericsson.com>
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From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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Subject: Re: [conex] Stephen Farrell's No Objection on draft-ietf-conex-destopt-09: (with COMMENT)
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On 08/10/15 17:02, Mirja K├╝hlewind wrote:
> Hi,
> 
> I'm fine with the text below. But a quick question: Is there really a
> case where the attacker would alter the packet to make another network
> potentially drop the packet, instead of juts dropping it on its own?

Good point. But I guess that'd provide a way for an attacker to hide
their tracks, though so yeah it probably could happen.

S.

> 
> Mirja
> 
> 
> On 06.10.2015 03:02, Stephen Farrell wrote:
>>
>> Hiya,
>>
>> On 06/10/15 00:43, Bob Briscoe wrote:
>>>
>>> [Proposal #2]
>>> A network-based attacker could alter ConEx information to fool an audit
>>> function in a downstream network into discarding packets. However,
>>> otherexisting attacks from one network on another such a TTL expiry
>>> attacks are more damaging (because ConEx audit discards silently) and
>>> less traceable (because TTL is meant to change, whereas CDO is not).
>>
>> That's better, yes.
>>
>> Probably no need to address it in this document but I guess our
>> assumptions about other existing attacks might change as more and
>> more network traffic is ciphertext at various layers. I'm also
>> generally leery of arguments of the form "no need to do something
>> here as there's a worse thing there" since those encourage us to
>> do nothing anywhere, so I'd lose that kind of language if it can
>> be done.
>>
>> S.
>>
>