Files Are Being Deleted Automatically

Question

Within the past week, we've had a couple complaints that users are receiving emails from O365 stating they have deleted a massive amount of files. As an admin, I investigate the files that are being deleted and in both cases, they are database files (temporary office files, Thumbs.db).

This is happening on Sunday when the users are inactive so it's a little alarming to them. What process is removing these database files and is our environment at risk?

Answer 1

Users who are synchronising SharePoint libraries or OneDrive for Business accounts with their machine may be unknowingly uploading files that are automatically generated by Windows such as Thumbs.db

If the user were to perform a cleanup on their machine, deleting many Thumbs.db files from their synchronised directory this may be flagged by Office 365 during the next synchronisation as a large scale deletion of files.