The image didn't attach to the question. Here it is.

That url isn't from mozilla nor firefox. Sounds like something from FB itself that is infected.

You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Such pop-ups are always a scam and clicking the button to proceed can give you malware even if you are on a Mac.

Thank you, all. Luckily, I did not click the button to proceed. The scan from CleanMyMac X was clean, but perhaps I will try to run some of the others. I didn't realize that different programs detect different issues. Thank you!

I'm still having the same problem. Here is another box that's popping up. Any other advice?

How do you end up on the websites that open such pop-ups? The URL that shows in the screenshot isn't a URL you would normally visit.

You can check for recently installed suspicious or unknown extensions.

• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Hi, they have been coming up when I'm on cbc.ca or Facebook.com. A new tab opens up (even when I haven't clicked on anything, I'm just scrolling) and the pop-up comes up.

Go to the Mozilla Add-ons Web Page {web Link} (There’s a lot of good stuff here) and search for a good ad blocker.

Thank you!

I suggest using uBlock Origin, https://addons.mozilla.org/firefox/addon/ublock-origin/

I hope this helps!

Have a chat with facebook and cbc and tell them to check their website. It may be an attack/hacker that has put an automatic redirect onto the site. It is a long shot but it's the kind of stuff that is happening now-a-days.

(Also, never click on links on these sites...ever...never!)