The recent ransomware attack on the city of Baltimore reminds us one more time of the importance of good cyber hygiene and patching vulnerable systems. In Baltimore's case, they were aware of the Microsoft vulnerability (and the availability of a patch) since 2017.... And yet, they had not patched their systems. If you know there's a thief in the neighborhood, one would think you would at least lock your doors. Certainly not foolproof and does not guarantee you won’t be a victim, but you can materially reduce your odds.
Note to NSA - more care must be taken to ensure your tools don't end up in the wild...