It is important to note that the devices reset were “ My Book Live hard drives”, connected over the LAN and not usb connected drives. The file server they used in the device was compromised.
It is generally a good idea to ensure that your internal network (wired and wireless) is not accessible from the Internet. If you need to allow access to webpages or controlled files either do it via cloud service rather than via your own network. If you must do it via your own network ensure that your network interface is configured to only accept incoming connections to the end points on your network that you have secured for external access.
Iain