"their" Whose addresses are known
The "CCVT thingies" you refer to. Unlike spoof
attacks these are easy to trace
and who are they known to?
Those who were attacked by them or worked on mitigation of
the attack. If not this time then they should next time
as there will be a next time.
Some work can produce Dyn allocations, I suppose.
Indeed, that is what I was saying