114
New ransomware wipes every file larger than 128 KB
(mashable.com)
This is a most excellent place for technology news and articles.
Overwritten is fine when that is intentional. But the best backups do include media that is completely offline and so if there is an issue you can restore to fresh/new uncompromised systems.
ZFS snapshots are great for this - so far they have not been attacked and when they work they give you what the file was before. (you still should have an offline copy of everything stored in a different campus)