As statet here:
http://www.gulftech.org/advisories/WDMyCloud%20Multiple%20Vulnerabilities/125
there are multiple serious vulnerabilitys in several McCloud Products. Including a Backdoor with hardcoded credentials for root access.
It is highly advised to disconnect the devices from the net.
Please read this posting as well as there is more information available. I just created this new topic as was adived in the old one.