A big online threat now is cryptohijacking. Malware is installed and the resource of either your PC or website used to mine Bitcoin.
Currently, WordPress and websites are been hit hard https://thenextweb.com/hardfork/2018/03/07/wordpress-cryptocurrency-mining-malware/
I recommend adding cryptohijacking extensions to your browsers. Please keep your computer anti-virus up to date. Please don’t open any attachments of email addresses you don’t recognise.
I recommend the following extensions to your Chrome or Firefox browsers. If you use Internet Explorer, Don’t.
minerBlock by CryptoMineDev
Ghostery – Privacy Ad Blocker
Chrome(if you must)
Avast Online Security 12.0.562 Avast Browser Security and Web Reputation Plugin.
Ghostery – Privacy Ad Blocker 184.108.40.206 Ghostery is a powerful privacy extension. Block ads, stop trackers and speed up websites.
minerBlock 1.1.16 Blocks cryptocurrency miners all over the web.
Update your anti-virus software and use preferably ones that now boast cryptohijacking or Ransomware blocking. If the software offers plugins to your browser then enable them as well as safe search.