[saag] can an on-path attacker drop traffic?

Michael Richardson <mcr+ietf@sandelman.ca> Wed, 02 September 2020 16:27 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
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Date: Wed, 02 Sep 2020 12:27:52 -0400
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Subject: [saag] can an on-path attacker drop traffic?
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I think most of us agree that an "on-path" attacker can read traffic.
They can problem inject traffic, and maybe even inject it in such a way that
it beats the real traffic.

I think that most of us can agree that an off-path attacker can not read
traffic.

So for instance, and on-path attacker can see the TCP SYN seq no or a DNS
query ID, and therefore answer correctly.
And off-path attacker has to depend upon implementation flaws to guess those
values. (Which at one point were very common)

A read-only on-path attacker that can read can be implemented with a MIRROR/SPAN port.
Or as we learnt a few years ago with creative bending of fiber.

A firewall or router is a potential on-path attacker, but it can also drop packets.
What do we call this?
This was historically called a MITM, and it implied all the attributes of
on-path.  But it is unclear to me if MITM > on-path, or MITM == on-path.

--
Michael Richardson <mcr+IETF@sandelman.ca>ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-