Subject: [manet] Warren Kumari's Discuss on draft-ietf-manet-dlep-pause-extension-06: (with DISCUSS)

From: Warren Kumari via Datatracker <[email-masked]>
Date: Mon, 08 Apr 2019 11:57:08 -0700

Warren Kumari has entered the following ballot position for
draft-ietf-manet-dlep-pause-extension-06: Discuss

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The document, along with other ballot positions, can be found here:
https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-pause-extension/

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DISCUSS:
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Please note that I'm really not a DLEP person, and so this may be completely
incorrect -- in which case I'm (of course!) happy to clear my discuss.

Hypothetical Scenario:
My next-door neighbor keeps using up all the bandwidth, making my Internets
slow! Stupid neighbor!

Until now I didn't have much motivation to mess with DLEP (it didn't really
gain me anything), but now I can spoof Pause Data Items to get the router to
stop sending traffic to her, freeing up all the bandwidth for me.

The security considerations section doesn't *really* cover this -- it says:
" Note that this extension does allow a compromised or impersonating modem to
suppress transmission by the router, but this is not a substantively different
attack by such a compromised modem simply dropping all traffic destined to, or
sent by a router." -- that only covers compromised modems, not impersonating
modems.

It also says:
"[RFC8175] defines the use of TLS to protect against the impersonating
attacker." -- yes, RFC8175 does indeed define the use of TLS, but doesn't
require it.

RFC8175 Security Considerations also say:
" This specification does not address security of the data plane, as it (the
data plane) is not affected, and standard security procedures can be employed."
and "Similar issues can arise if DLEP data is used as an input to policing
algorithms -- injection of malicious data via DLEP can cause those policing
algorithms to make incorrect decisions, degrading network throughput."

It seems that this specification is specifically allowing the dataplane to be
affected by (spoofed) DLEP messages, and in a much more direct way than
discussed in the RFC8175 security considerations section. I think that this is
dangerous without much more direct advice (like "MUST use TLS" or similar).

---

From: Lou Berger <[email-masked]>
Date: Thu, 11 Apr 2019 07:58:02 -0400

> https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-pause-extension/

FWIW an impersonator can shut a router completely down, by constantly 
resetting the DLEP session.  RFC8175 defines TLS protected DLEP as the 
solution.  To make this clear(er) the text has been updated to read

   Note that this extension does allow a compromised or impersonating
   modem to suppress transmission by the router.  Similar attacks are
   generally possible base DLEP, for example an impersonating modem may
   cause a session reset or a compromised modem simply can
   drop all traffic destined to, or sent by a router.  <xref
   target="RFC8175"/> defines the use of TLS to protect against the
   impersonating attacker.

suggested improvements are most welcome! (but see below addition before 
drafting ;-)

> dangerous without much more direct advice (like "MUST use TLS" or similar).

I have no objection to something.  How about, to the end of the prior 
paragraph:

   Implementations of the extension defined in this document MUST support
   configuration of TLS usage, as describe in <xref target="RFC8175"/>,
   in order to protect configurations where injection attacks are
   possible, i.e., when the link between a modem and router is not
   otherwise protected.

Lou

---

From: Warren Kumari <[email-masked]>
Date: Thu, 11 Apr 2019 09:30:07 -0400

On Thu, Apr 11, 2019 at 8:21 AM Lou Berger <[email-masked]> wrote:

> > Please refer to
> https://www.ietf.org/iesg/statement/discuss-criteria.html

Thank you, that works for me.

I'll clear my DISCUSS, and trust y'all to include it.
W

-- 
I don't think the execution is relevant when it was obviously a bad idea in
the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair of
pants.
   ---maf