Scammers are constantly finding new ways (or old ways) to distribute ransomware on your computer. Here's another article on how you can protect yourself. The most important takeaway is to show file extensions in Windows.
MacOS and iOS users: patch as soon as possible
The always excellent naked security blog at Sophos has released a warning against a major security hole in Apple software, including MacOS and iOS. We recommend patching as soon as possible to avoid becoming a victim of this malware.