Hi, there are a LOT of thread about that problem, so I'm not sure what you tried so far.

It is believed that the prompts are driven through online ads. Did you try using an ad blocking extension like this one:

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

Thanks for the suggestion, jscher 2000. I will try it even though previous blocker suggestions from the threads have not helped. If this works, I will be able to keep Firefox. If not, the incessant intrusions make it impossible to tolerate it any more -- after 12 or more years of satisfactory use. I do not trust Microsoft browsers or Chrome. Leaves me with few possible choices. I will see what happens now. Rokahaszn

Sorry to say jscher200, within minutes of installing the blocker, the same phishing window was popping up at will. Hopeless.

Hmm, stubborn buggers.

Are these download dialogs opening over the usual bizarrely named sites with a stolen Firefox logo or are you seeing something new/different?

Are you blocking any information that websites usually receive that might let them know they already tried to scam you today and they should wait until tomorrow? That might include cookies or headers.

Can you rule out a bad extension or malware?

Do you want to temporarily set Firefox to lie to sites and tell them you're running Chrome to see whether that makes any difference? Here's how:

(0) Select and copy the following new preference name:

general.useragent.override

(1) In a new tab, type about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste usera and pause while the list is filtered

Assuming this preference does not already exist from back in the old days:

(3) Right-click a blank area of the page, click New, then String

(4) Paste the preference name, then click OK

(5) Type a temporary value like X, then click OK -- the preference should appear in the list, bolded -- keep this tab open

(6) Select and copy the current Chrome user agent string:

Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36

(7) Double-click the general.useragent.override preference and replace the temporary value with the string you copied in step 6 and click OK

When you visit a site that reports on your user agent string, it now should tell you you're running Chrome. For example:

https://www.jeffersonscher.com/res/jstest.php

I don't know whether that will make any difference with this problem, but it would be interesting to test. Meanwhile, that may cause problems on some complex sites that tune their scripts to different browsers, so I don't recommend it as a permanent change.

To restore the normal value later:

(8) Right-click the general.useragent.override preference and choose Reset to clear it.

Appreciate the effort jscher 2000. Regrettably none of these things work. In fact, this constant popup is more like an independent window and instantly appears after Firefox is started. Clearly this problem has been around for many months at the very least, and in all that time Mozilla has not -- cannot -- do anything to stop it. I am coming to the conclusion that if Mozilla cannot stop it, the only thing left is to abandon Firefox. What else can Mozilla not do if it can't even stop this? And to boot I get the impression that they are not too concerned about it. So the burden is on us, the users.This is a side effect of free software -- no vested interest in keeping users. Well, I have reached the point of total mistrust and frustration. Cannot put up with this any longer. Plus I am at a loss what to replace it with.. Bad, sad business.

Please try this and if one of the programs finds issues please correct them. If still having issues it is recommended that you do follow it up in one of the programs forums.

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

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

Dear Pkshadow, Thanks for your interest. Since you do not have any way of knowing all the things I have done to try to deal with this problem, I understand that you would recite the same things I have seen and studied at length long ago. Not a single suggestion in those articles make the least difference. I have installed a variety of popup blockers, but none of them is ever triggered by this intrusion. Is it even a popup? It is 4 by 5 inch window titled "software update." I cannot determine where it comes from, and does not look like a usual "popup." It offers a bogus update which other users have discussed of the forums. Within seconds of starting Firefox these windows appear again and again. They can be closed and they come back constantly. During the reading and answering your post I have had them come up half a dozen times already. They appear on all 4 of my computers, which share only the fact that they have Firefox as the default browser. Otherwise they are of different hardware, are used for different tasks. If this is malware, various malware elimination programs do not identify it. Clearly the target is Firefox -- since that is what this thing offers to update. Instead of all the general articles about popups and malware, it seems to me that Mozilla itself is under siege and as far as I can see it has done nothing I can locate to combat it -- this has been going on for over a year or more and is getting worse. I am amazed that Mozilla has nothing to say and apparently no inclination to do anything about it -- or else this thing is so "clever" that Mozilla is helpless. So far none of the items and articles offered by the forums has done anything to deal with this issue. That is why I am on the verge of having to abandon Firefox. No amount of references and articles are going to solve this by the end user, and the Mozilla organization is apparently oblivious. I have done everything I can with no effect and see nothing left but to stop using Firefox. Rokahaszn.

Do a malware check with several malware scanning programs on the Windows computer.

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

Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

Rokahaszn said

Within seconds of starting Firefox these windows appear again and again. They can be closed and they come back constantly.

Do their addresses show up History?

How do you close them? For example, are you canceling a download dialog and then closing the tab?

Dear cor-el I am willing, as time allows to run those programs in your list which I have not tried yet. Am pessimistic.

Dear Jscher2000 The offending window does not appear in History at all. I close them by clicking the "X" mark in the upper right corner the same way one would close any open window.

To all those who are trying to help: Thanks! But based on the questions being asked, these windows seem not to be familiar to some of you. Yet I see entries regarding this by other users indicating that I am not an unusual victim. I wish someone who actually had the experience and managed to defeat it would put in a post

We understand the issue and time constants as we volunteer or time here.

Without running the programs you will not have completed the support we are trying to offer you. Please run the programs and make sure you save the log files from them as they will be needed in Malware Forums of your choice.

Please run the programs.

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

Dear Pkshadow. I have visited all the links provided by cor-el. One of them was blocked by McAfee Total Protection as unsafe. Hoe do I know if these programs were really doing useful things or were disguised malware?I already have Malwarebytes and ran it again. I downloaded and ran those that I could. Several were obscure and confusing. The Microsoft product ran a full scan for over an hour. The informational articles contained nothing I do not already know. The Kaspersky links all go to their sales site only. I already have an antivirus program, do not need Kaspersky. The total result of all this effort was one ad and a few cookies found, nothing else. If this fixed anything, I will be very surprised. Grasping at straws. I made the effort. Of course they all wanted to sell things. One could spend a fortune and never know if it is of any use. Thanks. Rokahaszn

Rokahaszn said

The offending window does not appear in History at all. I close them by clicking the "X" mark in the upper right corner the same way one would close any open window.

Web page windows should appear in history, unless history is disabled (e.g., automatic private browsing). Does the address bar appear in the window? You can compare the attached images featuring different kinds of popup windows and download dialogs.

If they are download dialogs, some users have reported odd situations where downloads keep resuming even if they are canceled. I can't recall how you purge those from Firefox's queue, but another volunteer might remember.

To Jscher2000: I have just lost a long answer I was writing to you when my reply window just disappeared and I was back in Firefox on the Mozilla search page! Now I will write my answer in Word and paste. As I suggested in my post of 7/3 it is apparent that many if not all of you who are trying to help have never been a victim of this thing and have never seen the window I am talking about. This makes it all the more difficult for you to help, not having had the experience, and this leads you down paths which do not reflect a successful solution that you have personally seen or found. Other posters who have had the problem and for whom “answers” were posted do not work for me. To answer your questions I agree that a window should show in History – yet it does not. I have not purged or disabled History. Since you have clearly never seen this window, it is a 4 by 5 inch window with a title strip containing “Software Update.” On the right upper corner the usual minimize, maximize (greyed out, the thing cannot get resized) and the “X” to close it. The body text offers a Firefox update to “version 53.” The are buttons below to install. I have not found any way to get a URL or any clue to the sender. As for downloading, that is not an issue, and I am quite familiar with the images you attached. Fortunately it does not launch its download, and if it did, I would do an instant hard shutdown. I close it with the “X” and it comes back at odd intervals, sometimes within seconds, and only while Firefox is running. If I am using a server such as Origin I do not get it. I see it on all of my computers with Win 10 Home, Win 10 Pro, and Win 7 if I run Firefox. I have totally uninstalled Firefox and reinstalled it from the Mozilla site – it has not stopped the problem. I am not a heavy downloader of software, certainly never anything questionable in my opinion. I use Firefox for searches, some Youtube classical music and documentaries and mostly productivity purposes. I do not do any idle browsing, I do not chat, use social media of any kind or watch pornography. All but one of my computers are fairly high-end gaming machines, custom assembled from components of my choosing and all different in hardware configuration. All have a few programs I use across all platforms and all have Firefox. But the majority of the programs on each are different from each other. Therefore I believe that only Firefox is the focus of this issue. I fear that until a volunteer who has personally seen and dealt with this problem has any chance of sharing any firm information. I hope I have given all relevant information I can think of, and keep hoping for a volunteer who has seen and succeeded in killing this thing. Thanks again for all efforts to offer help. Rokahaszn

Rokahaszn said

Since you have clearly never seen this window, it is a 4 by 5 inch window with a title strip containing “Software Update.” On the right upper corner the usual minimize, maximize (greyed out, the thing cannot get resized) and the “X” to close it. The body text offers a Firefox update to “version 53.” The are buttons below to install. I have not found any way to get a URL or any clue to the sender.

It would be helpful if you can post a screenshot of the window/dialog. Firefox's built-in notification dialog has Software Update in the title, but the exact buttons vary depending on whether you have Firefox set to notify you of updates or install them automatically. Users have reported cases in which an update becomes stuck and the update notification keeps appearing over and over, even if it is no longer needed. (I don't recall where you delete the folder containing the update.)

To jscher2000: I will try to get you a screenshot. At present I am quite busy with other things and have been doing less online activity. And I do have Firefox notify me of updates and they do not look anything like this malware. They are full-screen Mozilla update reminders. And I even go to the Mozilla site and download the current version rather than clicking on “update” just in case. This is NOT the real Mozilla notification, and the “version” offered is a nonexistent one, usually a higher number than the real current version. My hope for a short thread with an easy answer has become anything but. Rokahaszn

For one we would not recommend them if we did not think that these were the appropriate programs to run and to determine and possibly fix your issue or to give you the logs to go to other malware sites to have them explained and looked at and to follow their directions to remove your issue. These programs are top of the line for malware fighting, as is their support forum.

Mcafee does not catch everything, these programs must be run to determine in the log files what is going on. You do not have to repair anything. You need to scan and get a log file and submit it to a Malware Forum.

We do not deal with malware here. Please do not send a screenshot, save it for when you seek help in a Malware Forum

You run the programs or not is your choice, or find others that you may think are better.

You need to do this as there is no further support that we offer on this issue.

(sp)+(punctuation)

Rokahaszn said

I will try to get you a screenshot. ... My hope for a short thread with an easy answer has become anything but.

Thanks. Hopefully the picture will save some of the proverbial 1000 words.

To Pkshadow, My post of 7/3/17 says all i need to say regarding my visiting all the sites kindly provided by cor-el and my report that none of them found anything. Only a few had (or perhaps I only found) log files. These listed all the items checked and confirmed that nothing was found except an ad and some cookies by one of those programs. I am unable to see what you find obscure or unsatisfactory in that report. You have the advantage of me in that I know nothing of who or what you are or what your position is beyond volunteering your time to assist other users. I certainly do not intend to be acrimonious with you and thank you for your time. Although I was using an IBM mainframe at Dartmouth when Professor Kemeny introduced time-sharing in the 1960’s long before personal computers even existed – and have been using computers ever since – I do not claim any expertise in current software engineering. Thus my call for help. If you disapprove of my conversations or opinions, I hope you will simply abandon me to those who are willing to communicate with me, inasmuch as you clearly state that you have no help for me. This suggests you need to ignore this thread. I will send the screenshot asked for by jscher 2000, it is simple courtesy. Other respondents have sent ME images, and those apparently did not cause you any upset. As for Malware, it is yet to be determined if this thing IS Malware. Your ordering me off the thread is a bit premature. I continue to hope that another volunteer who has struggled with this issue and found a solution might happen to find this thread. If in fact such a person has determined that it is Malware, then you will have a valid point – except that none of the recommended programs found Malware.. Meanwhile I hope that freedom of expression is a valid concept for you. All the best, Rokahaszn