No need for extensive Linux experience: Use a secure password for DSM, turn off "EZ-Internet" and other DynDNS-like services, make sure it's connected to your router and not directly to the Internet, don't forward any ports, don't enable DMZ or similar functionality on your router, keep up-to-date with DSM updates, make sure other computers on your network are malware-free (there could be a piece of PC malware exploiting synology devices found on the local network), keep multiple backups in different locations (online and offline) of your most valuable data.

These are just best practices, since we don't know anything about this particular piece of malware yet. They should cover most threats and worst-case scenarios.

If you need access to your Synology device from outside your home network, use a VPN or an SSH tunnel.