Most US critical infrastructure is run by private corporations. This has major security implications, because it’s putting a random power company in — say — Ohio — up against the Russian cybercommand, which isn’t a fair fight.

When this problem is discussed, people regularly quote the statistic that 85% of US critical infrastructure is in private hands. It’s a handy number, and matches our intuition. Still, I have never been able to find a factual basis, or anyone who knows where the number comes from. Paul Rosenzweig investigates, and reaches the same conclusion.

So we don’t know the percentage, but I think we can safely say that it’s a lot.