Defenderweb.xyz Tries to Push Ads Through Scare Tactics
Defenderweb dot xyz is a misleading website, set up to scare visitors and to get them to approve push notifications.
If you end up on Defenderweb dot xyz, most likely after clicking a rogue ad on a different page and being redirected to the site, you will see a scary message, informing you that your PC is infected with nondescript "viruses". The image shown with this text on it also uses legitimate branding of an antivirus product illegally, to lend an air of credibility to the scary but fake message. It should be noted that sites like Defenderweb dot xyz have nothing to do with the legitimate products whose branding and logos they often abuse.
Along with the scary message, your browser will also show you its default "allow notifications" box. If you click "allow", you will permit the website to send intrusive, annoying and potentially dangerous ad pop-ups to your browser. The ads displayed in those pop-ups will often originate from rogue ad networks and may expose you to further misleading pages or malware.
Just remember that a random web page cannot know if you have viruses on your computer and simply navigate away or close the browser when you run into a similar setup.