Lars Prehn wrote on 20/10/2022 20:23:
If you want to know more about the research that initiated this
notification (including our concluded private disclosure process), you
may find a write-up at:
https://arxiv.org/pdf/2210.10676.pdf
Lars,
thanks for sending your findings to routing-wg. The impact of
deaggregation of ipv6 prefixes on router resources has been understood
since well before ipv6 was standardised.
Your paper describes an attack which can either use a provider's
customer cone or else use a selection of different transit providers to
inject smaller numbers of prefixes from different injection points into
either a providers routing table, or the ipv6 dfz. Your argument is
roughly equivalent to stating that if you send 20,000 cars from
different starting points to a single destination, that you will end up
with gridlock, as the taxi industry in Moscow discovered a couple of
weeks ago - this isn't news for either cars or routing table prefixes.
There are many other easily-staged attacks which are also efficient at
causing disruption, e.g. sending 1tbit/s of data at a destination,
gluing oneself to the road on a commuter trunk during rush hour, cutting
fibre cables in chambers, etc. All of these are low cost, regularly
tested, and are known to work well.
Your list of takeaways in section 6.1 is correct, but it stopped at the
point of detection and mitigation. Routing tables are monitored, and
some people / organisations have alerts triggered, particularly transit
providers. Another is that routing operations people tend to notice
things like routers and routing tables blowing up. In other words, you
will cause damage if you try this in anger, but fairly quickly the
source(s) will be noticed and you'll find that mitigation action will be
taken. As quickly as providers might increase prefix limits on a bgp
session, they will drop them too, or shut down the session entirely, or
terminate your free ipv6 transit, or cut off your ixp peering.
This is important because one of the more important aspects of network
reliability is not closing off all angles of potential attack / failure,
but ensuring that detection and time-to-recovery are optimised.
The Vultr incident on October 5 this year was noticed fairly quickly on
operator forums, both because of alerting on router FIB resource usage
and control plane CPU usage. Incidentally, production de-peering
happened as a result of the incident, although hopefully that has been
undone at this point.
Nick
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