Crypto Locker Trojan/Virus will cripple your computers! The usual delivery of the attack is via an e-mail disguised as UPS/USPS/FedEx. Keep in mind that these parcel services DO NOT send out attachments! Just delete the e-mail if it comes from ups.com, usps.gov, or, fedex.com and has an attachment. Also, the hackers are getting this virus around most anti-virus solutions and spam filters; probably by changing up the code and pushing the e-mail through legitimate mail servers on the web. One I investigated came through a citibank.com server in London.
They are also known to use ADP as a front.