You can disable
autofs if you don't need it. This will prevent to mount automatically removable media or NFS filesystems.
You can simply write an udev rule to disable automounting.
First, create the file
sudo vi /etc/udev/rules.d/85-no-automount.rules
and add the following lines:
Restart the service:
sudo service udev restart
This will prevent any USB device from being mounted by the udisksd daemon. If the service didn't work, you might need to reboot the server.