The authors of the TeslaCrypt ransomware have improved it by implementing new sophisticated evasion techniques and targeting new file types. TeslaCrypt 4.1A is only a week old and contains an even greater variety of stealth and obfuscation techniques than its previous variants. The new strain of Teslacrypt is spread as attachments of spam campaigns purporting to be shipping delivery notifications. Ransomware attacks are the headlines in this first part of the year, and the situation is worsening, according to experts at Endgame Inc.”]
Source: https://securityaffairs.co/wordpress/46523/malware/teslacrypt-4-1-a.html