Do these seem to come up on pages with lots of ads, or on sketchy sites, or just out of nowhere?

One way to reduce exposure to dangerous ads is to use an extension that blocks ads. This one is popular:

https://addons.mozilla.org/firefox/addon/ublock-origin/

Some sites do not work correctly with ads blocked, so you will need to use its toolbar button from time to time to make exceptions. It's up to you to decide whether the hassle is worth it.

Most prevalent is my.xfinity.com login page, lots of ads. Are these coming from ads on that particular page hosted by Comcast?

Next would be Yahoo.com, same issue.

I'll check out this ad blocker.

Yes, most likely, the ads are injected by the websites. Ublock Origin will block all that stuff for you.

The version of Firefox that you used to post here shows Shockwave Flash 27.0 r0 which is not the current version of Flash.

Adobe Flash Player 29.0.0.140 is the latest version and it needs to be the NPAPI version. Since there are different versions of Flash for Firefox (NPAPI), for IE (ActiveX), and for Chrome (PPAPI) all 3 need to be up-to-date if you use those other web browsers.

Is there a reason that you don't want to update Flash for Firefox?

joat_65 said

Next would be Yahoo.com, same issue.

Yahoo pages was actually a common place for people to encounter a certain Fake Urgent Firefox Update page mentioned here due to malvertising like on some Yahoo pages back in second half of 2016 and first part of 2017 then.

As said your Flash player 27.x is not close to being current as the last 27 branch version was 27.0.0.187 released back on Nov 14, 2017.

https://get.adobe.com/flashplayer/otherversions/ https://get.adobe.com/flashplayer/about/

Thanks for verifying the version I had (updated to V 29). I was under the impression it was current. I was also unaware there are different flash players for different browsers (I knew Edge was different but not Chrome). I will check them as well. I would rather not use Flash at all but it seems to be the default player to watch stuff.

But still, this really has no effect on the the malware pop-ups showing up on my PC, correct?

Could someone explain: "ads are injected by the websites". I want to understand because I believe it's a Comcast issue (their web site) and they won't take ownership.

Hi, Do Not Update Edge or IE with Flash, You must use Windows Update for those. While there there maybe a 700meg update to come in.

The ads are there with code that causes the issue. They will never take ownership so no point in that, do things as per Ublock Origin and Ghostery , HTTPS EveryWhere, Norton Safe Web, you can find from below : https://addons.mozilla.org/en-US/firefox/extensions/

Scan your self as you may have downloaded something that causes the issue, use malware scanners as per :

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

If need Help :

• https://forums.malwarebytes.com/topic/9573-im-infected-what-do-i-do-now/

Please let us know if this solved your issue or if need further assistance.

It's been a few days since I've installed uBlock Origin and have not seen the (fake) Flash Player Update popup. I've had to add a few sites into the white list but things seem fine. I will continue to investigate the additional links supplied in this thread to try and find out more on why I get these.

Thanks