Ransomware and OneDrive
So it looks like Microsoft has active measures that detect when something goes through and encrypts your files. Ransomware encrypts your files deletes your backups and file history and then demands money in the form of bitcoin.. It's good to know onedrive is watching out for this and will store a previous copy of the files and allow you to retrieve them after you remove the ransomware.. just one more reason to use OneDrive. Here is Microsoft's article.