We had a customer infected with cryptowall this week.  Thankfully the server was backed up well so most of his files were recoverable.  He had a few personal files that were stored on his local drive that were not.  These new ones are very nasty.  There is no decrypt tool.  You need a backup or to pay the ransom or you are not getting your files back.   The new ones also scan shared directories so your server files are not safe.  Update your pcs.  Get ride of windows XP.  Make sure you have up to date virus protection.  Backup.  Do not not ignore the virus protection warnings.  Be safe out there.