The FBI is analysing a strain of ransomware called MSIL/Samas that tries to encrypt data across entire networks rather than single computers. http://www.bbc.com/news/technology-35916425
More detailed info on this bugger here: https://blogs.technet.microsoft.com...mas-whats-in-this-ransomwares-modus-operandi/ Important to note is this is not delivered via e-mail.