Re: [DNSOP] DNSOP: question about hardening "something like mDNS" against attacks

Jared Mauch <jared@puck.nether.net> Mon, 26 October 2020 21:17 UTC

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Date: Mon, 26 Oct 2020 17:17:30 -0400
From: Jared Mauch <jared@puck.nether.net>
To: Ted Lemon <mellon@fugue.com>
Cc: Toerless Eckert <tte@cs.fau.de>, Jared Mauch <jared@puck.nether.net>, dnsop <dnsop@ietf.org>, kaduk@mit.edu
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Subject: Re: [DNSOP] DNSOP: question about hardening "something like mDNS" against attacks
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On Mon, Oct 26, 2020 at 04:39:10PM -0400, Ted Lemon wrote:
> What actually hardens mDNS is that it’s a link-local protocol. 
> It doesn’t work across links. This limits the attack surface. 

Exactly.

> But there’s no way to eliminate the attack surface.  If I were in Ben’s shoes, 
> I’d be asking you to change the protocol to support authentication and 
> ToFU as a hardening strategy, with some better trust establishment mechanism 
> as future work based on the existing presence of crypto signatures. But 
> the current consensus of the IETF is apparently that ADs aren’t allowed to 
> insist on things like that. :(

We must also consider that mDNS is meant to provide that on-link communication
for devices that are perhaps not professionally managed, such as my
home where I may want to talk to raspberrypi.local or my printer
or other on-link device without placing it in some enterprise or other
lookup system.  This helps prevent remote attacks and discoverability of
my devices and provides security this way.

- Jared


-- 
Jared Mauch  | pgp key available via finger from jared@puck.nether.net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.