I didn't want to post yet another SECURITY ALERT post, lest I have to change the name of my blog to SECURITY ALERT - 2018 EDITION; but if you use a Western Digital "My Cloud" hard drive, you need to update the firmware as soon as possible, or better yet disconnect it from the internet.
The My Cloud drives from Western Digital allow you to access your files if you're away from home. Unfortunately, it turns out that WD hardcoded a backdoor into the drive. What this means is that anyone can connect to the drive using a username and password that is plastered all over the internet (but I'm not posting it here).
WD promises the latest firmware update fixes it, but as far as I'm concerned they aren't taking security very seriously in the first place if they let something like this through, and my recommendation would be to disconnect it and use another brand of drive.
The drives that are affected are the MyCloud, MyCloudMirror, My Cloud Gen 2, My Cloud PR2100, My Cloud PR4100, My Cloud EX2 Ultra, My Cloud EX2, My Cloud EX4, My Cloud EX2100, My Cloud EX4100, My Cloud DL2100, and My Cloud DL4100.