In most cities, nobody owns the whole network

Editor’s note: Waco bought the network segmentation technology described here from Elisity while Mike Searight was the city’s chief information officer. He is now a senior adviser to Elisity, a cybersecurity company.

I stood in front of a network cabinet at one of Waco’s water treatment plants, tracing what systems could reach which. The plant’s controls were on that network. So was the branch library. So was the register at the municipal golf course. During my time as chief information officer of a city with 145,000 residents, nobody had ever been asked to inventory what was on that network.

In July, intruders compromised water and wastewater treatment equipment. Most of that equipment was reachable over public cellular networks, which means they were outside the boundary most utilities thought they were defending. None of the asset lists I have reviewed would have caught it.