Actually two PSAs.

First: Especially if you're running Windows, you ought to go read The Untold Story of NotPetya, the Most Devastating Cyberattack in History | WIRED. It's the story of how a worldwide shipping company was taken out as collateral damage in the ongoing cyberwar between Russia and the Ukraine. Three takeaways:

  1. If you're running Windows, keep your patches up to date.
  2. If you're running a version of Windows that's no longer supported (which means that you can't keep it patched, by definition), either never under any circumstances connect that box to a network, or wipe it and install an OS that's supported.
  3. If at all possible, keep encrypted offline backups of anything really important. (I'm not doing that at the moment either. I need to fix that.) If you're not a corporation and not using cryptocurrency, cloud backups encrypted on the client side are probably good enough.

Second: I don't really expect that any of you out there are running an onion service. (If you had to click on that link to find out what it is, you're not.) But just in case you are, you need to read Public IP Addresses of Tor Sites Exposed via SSL Certificates, and make sure that the web server for your service is listening to 127.0.0.1 (localhost) and not 0.0.0.0 or *. That's the way the instructions (at the "onion service" link above) say to set it up, but some people are lazy. Or think they can get away with putting a public website on the same box. They can't.

If you're curious and baffled by the preceeding paragraph, Tor (The Onion Router) is a system for wrapping data packets on the internet in multiple layers of encryption and passing them through multiple intermediaries between you and whatever web site you're connecting with. This will protect both your identity and your information as long as you're careful! An onion service is a web server that's only reachable via Tor.

Onion services are part of what's sometimes called "the dark web".

Be safe! The network isn't the warm, fuzzy, safe space it was in the 20th Century.

Another public service announcement from The Computer Curmudgeon.