Security firms have reported a major spike in TeslaCrypt ransomware activity over that last two weeks. The recent surge is likely attributed to the holiday shopping season when users are shopping online and more likely to beeing duped into opening malicious emails.
Here are two articles discussing the topic in detail.
http://www.symantec.com/connect/blogs/major-teslacrypt-ransomware-offensive-underway
http://www.infosecurity-magazine.com/news/teslacrypt-reappears-with-savvy/
