Subject: [secdir] SecDir review of draft-ietf-grow-blackholing

From: "Paul Hoffman" <[email-masked]>
Date: Sun, 26 Jun 2016 17:14:40 -0700

This draft, "BLACKHOLE BGP Community for Blackholing", describes a new 
optional BGP community with the specific semantics of "please blackhole 
this traffic for me". The idea is to have a single common community 
instead of all the ad hoc communities that ISPs have created for this 
semantic.

The beginning of the security considerations section is daunting in that 
it says, in essence, "BGP has no authentication, so injecting dangerous 
messages is trivial; thus this new dangerous community is not a 
problem". It then goes on to say "and this new community can be used as 
a DoS by your downstream peers because they can tell you lies, but you 
were already susceptible to those lies". And then "and this can be used 
for CPU exhaustion against you if you're not careful" without saying how 
to be careful.

There are currently two active threads on ietf@ about security 
implications of this draft. There are questions about whether this draft 
lacks enough specificity to prevent CPU exhaustion attacks even from 
well-meaning peers, whether it should be standards track given that it 
is underspecified, whether it should suggest that IXPs should implement 
it, and other questions seem to be coming up.

I think that this document *might* be OK as an Informational RFC if 
there is more discussion about how to prevent a CPU exhaustion attack 
for recipients and more MUSTs instead of SHOULDs for what other 
communities need to be applied to these messages.

--Paul Hoffman