If you are running a Linux web server, this threat is currently in the wild. An ounce of prevention is worth many pounds of cure in this case, since the ransomware asks for a single Bitcoin (currently over $420) to decrypt your files.

http://techcrunch.com/2015/11/06/linux-ransomware-is-now-attacking-webmasters/

Don't run anything as root unless you are certain of its origin and purpose. A vigilant user or sysadmin is still the best defense against these threats.

DR