CryptoWall is malicious software that encrypts files on an infected computer, including any files accessible on attached USB drives, network drives, and any cloud sync programs like Dropbox & OneDrive.
The big thing to watch out for is unsolicited emails from people you don't know.
There are currently coming in the form of a CV / Resume and the attachment is in a ZIP file.
If you get anything like this delete it and DO NOT open the attachment!
This of course could change at any time so please be aware of any email attachments from people you don't know or if you weren't expecting the email.
You can read more information about it here.
Make sure you have regular backups and don't leave your backup drive attached to your computer all the time as the files on there would also become encrypted if you got infected.
Make sure you have a good antivirus program and that it is up to date.
If you need any help with backups or antivirus software please contact Conex.