The threat from RansomWare is very real, and still very current. Please check out http://www.publicsafety.gc.ca/cnt/rsrcs/cybr-ctr/2013/in13-004-eng.aspx
and also
http://www.techrepublic.com/article/cryptowall-what-it-is-and-how-to-protect-your-systems/

I highly recommend you install CryptoPrevent from
http://www.foolishit.com/vb6-projects/cryptoprevent/