The worst virus I had is when a 14 year-old German boy thought it was funny to completely shut down my computer and go through all my files, and now he is in jail. Then, I got a trojan horse virus, it was pretty bad. At first, I thought you could close it, but apparently you can't. After these difficulties, I got DDoS attacks all the time. I setup DDoS Protection from DigitalOcean, and got some virus inspector programs such as McAfee, Avast, and Norton, but I highly recommend McAfee.
Thank you,
Charlie.