Definitely I would say your system has been compromised. I would definitely reinstall GhostBSD on that drive. If you're feeling adventurous you may want to try to reproduce what happened and record it this time if it's not too much trouble.
Reinstalling GhostBSD should fix the problem completely. If you really want to be safe, there is free software available called Darik's Boot and Nuke. You can find out about it here
https://dban.org/ .
This software will pretty safely wipe your hard drive of all data. I've used it and it works well but it can be slow depending on what wipe options you choose.
Your best option would be talking to someone who knows more about this kind of thing than me. If you know someone personally that could check your drive and find out what happened that would be great.
You asked before if you thought it may have been flash causing the problem. If you want to find out if flash is installed on GhostBSD. type this command as normal user
pkg info flashplayer
if it's installed, you'll get output something like this:
flashplayer-32.0_1
Name : flashplayer
Version : 32.0_1
Installed on : Fri Jan 25 20:32:59 2019 JST
Origin : www/flashplayer
Architecture : FreeBSD:12:*
Prefix : /usr/local
Categories : multimedia www
Licenses :
Maintainer :
emulation@FreeBSD.org
WWW :
https://www.adobe.com/
Comment : Native wrapper around Linux Flash Player
Annotations :
repo_type : binary
repository : GhostBSD-ports
Flat size : 0.00B
Description :
Wrapper around Linux Flash Player that allows native browsers to display
Flash content.
WWW:
https://www.adobe.com/
if it's not installed you'll get:
pkg: No package(s) matching flashplayer
If you decide to reinstall GhostBSD, please let us know what you think on the forums here or the Telegram channel
All the best