If you use a WD My Cloud drive, you should check as a matter of urgency that its firmware is fully updated. This is because earlier firmware versions are vulnerable to an exploit which is now widely known, and can be attacked remotely.
Full details have been released by GulfTech Research and Development, and affect firmware versions up to and including 2.30.165. Upgrading to firmware version 2.30.172 or later is believed to secure the drive from this vulnerability.
Firmware updates are available from WD here.
Note that some reports are claiming that My Cloud drives should be disconnected as they are still vulnerable: this does not appear to be the case according to GulfTech or WD. Provided that they are updated to the current firmware release, you should still be able to use them normally.