Help Me with Firefox Popups

by Preston Gralla

I'm a big fan of Firefox and its built-in popup blocker. But in recent weeks I've noticed an alarming trend: an increasing number of popups and pop-unders are slipping under the Firefox radar, and appear without warning on my screen.

I'm not along in noticing this. Quite a few people have had the same problem, and they've emailed me, asking if I know why this is happening, and how to stop it.

The answer, unfortunately, is no -- I haven't been able to find a fix, or even understand how these annoying windows manage to appear on my screen.

So I'm asking for your help. Do you know how these popups and popunders get by the Firefox popup blocker? More important still -- how can I kill them? If you know the answers, or just have ideas, post a comment and let me and the world know.

Why are popups and popunders evading the Firefox popup blocker? If you know why, and how to fix it, let me know.

2005-03-30 11:29:07
Can you give an example offending page?

Can you give an example offending page?

2005-03-30 11:56:55
Example and possible reason
An example would be helpful.

If I remember correctly, this is being caused by Flash multimedia objects, which now seem to be one of the mediums that advertisements are being distributed. The Flash plug-in is allowed to open URL's in new windows, which it can do at anytime. You could block the plug-in from spawning new windows, but this would also block desirable new windows. :/

For lots of great info just on this particular topic, check out Asa Dotzler's blog posting

2005-03-30 12:48:45
I have an idea
I believe (and have read) that this new breed of popups is primarily caused by Macromedia Flash.

Firefox is set to block popups caused by the standard code that makes up web pages. Flash however is a plugin with rights to open popups on its own. Unfortunately, if you block it's ability to do so, you may hinder safe Flash content from performing as designed.

My solution is to use the FlashBlock extension for Firefox ( FlashBlock replaces Flash content with a placeholder on the page that allows you to click to view the content. It has a whitelist so you can turn on Flash (for every visit) on pages you trust.

I have used this extension for some time now simply because advertisements were becoming too distracting - hindering my reading. I noticed that popups began appearing on one of my computers that did not have Flashblock installed while I saw no new popups on those with it.

I hope this helps.

2005-03-30 12:52:43
I have seen this too and they are difficult to reproduce because (I think) it usually comes from a banner-ad, which changes on refresh. If you start reading dilbert every day, I think you might run into one.
2005-03-30 12:59:12
The answer is...
To block pop-ups from plugins, open your Firefox 1.0 or 1.0.1 browser, type about:config in the address field. Right-click in the resulting config page somewhere and select New -> Interger. Type privacy.popups.disable_from_plugins in the resulting dialog, hit OK, type 2 in the next dialog and you're all set.

This pref can actually take three values:

* 0: open allowed
* 1: the opened windows are treated as popups, but they're allowed to open (we limit the number of these types of popups)
* 2: the window is a popup, block it

2005-03-30 14:56:47
An Example of an offending site
Everytime I visit one of these pop-ups appear.

After making the Config File changes as suggested, I have noticed the pop-up that would always sneak by is now blocked.

2005-03-30 15:45:42
Easy answer
Just google for Proxomitron
2005-03-30 16:40:50
Privoxy requires a reasonably Linux compliant system, such as Mac OS X. For Firefox based solutions, take a look at the Adblock extension.
It is mostly useful for sites that you frequent, and also blocks Flash nicely.
Perhaps some of those popups are really floating iframes? Use Adblock.
Adblock lets you import its filters from a plain text file. Consider offering shared adblock.txt files to our community! I'd be happy offer mine, under GPL or other license.
2005-03-30 17:57:05
So don't go there...
The problem you are encountering is not surprising. As popup blockers become more common, the folks who think they are effective ad forms get more creative in ways to produce them that aren't blocked. Mozilla based browsers such as Firefox block popups by disabling the Javascript "open unrequested window" function. The stuff you see now is probably using something other than Javascript to create the popup.

There are several options, though none are transparent. Under IE, I used to run a program called Naviscope. Naviscope functioned as a proxy server. I pointed Naviscope at my network connection, and told IE to connect through Naviscope. Among other things Naviscope filtered ads and blocked popups. Another popular product like that was the Proxomitron, which functioned in the same fashion. The drawback was the need to configure them for optimal performance, which might require site-by-site tweaks to handle special cases. Most users likely lack the knowledge to do that efectively. Some of us who have the knowledge begrudge the time required.

Developers have created a couple of extensions for Mozilla products that can help, such as AdBlock and FlashBlock. I've also encountered an extension that tried to amke it easier to train AdBlock.

Personally, I haven't gone that far yet. I use the built-in popup blocker of Firefox, and I've installed a set of CSS rules that blocks most in-line ad content. I suppose I'm lucky, as the sites I visit haven't resorted to the more advanced (and annoying) forms of pop-ups/pop-unders. Sites that do will probably lose my visit, and may get a note to the webmaster saying I won't be back and why.

The big question is "Why visit a site that has this crap in the first place?" In my case the answer is "Only if the site has something I need and can't get elsewhere". So far, I haven't seen any sites that qualify.

2005-03-31 05:03:37
The answer is...
Also, there's a privacy.popups.firstTime preference in about:config that's set to False. This worked for me, killing a couple of the new-style popups with no ill effects. Note that these prefs are undocumented and may have side effects...
2005-03-31 16:05:24
An Example of an offending site
I've never seen them but then I have adblock stopping everything from so that might be the reason.

2005-03-31 22:51:04
Get the fix - Popups Must Die!
The current rash of popups are coming from two sources: flash, and click-event hitchhikers. There are a couple of ad-servers in particular who throw every trick in the book at the visitor, hoping one of them will work depending on what browser they're using.

We've posted an extension that simply blocks all new windows. It stops the unwanted popups but at the cost of requiring explicit whitelisting for desired popups.

Because it's an extension it's easy to remove if you feel it goes too far. We're thinking of making these the default settings in the next version of Firefox so we welcome your feedback.

Read more at Asa's notblog

2006-04-11 04:49:41
when I use my internet i notice windows 2000 being installed in my system how to avoid that any solution?
Richard Jones
2006-05-02 01:06:38
I've got a popup from this page:

It doesn't appear on first load, but does appear later.

Note that I don't have Flash in my browser, so this isn't a Flash-based pop-up, but some other sort of exploit (a fairly apt word for this).


2006-05-03 10:25:49

In older versions, firefox had an option to show the message of a popup blocked in the Status Bar instead of showing that big yellow bar up the page screen.
Is this option available on firefox

2006-05-16 16:54:45
MozillaZine has a knowledge base article on this:
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Casey C
2007-02-23 11:20:02
Well I use a extension called adblock plus. It seems to work great. I get about a pop up a week, try it out.
2007-04-04 19:22:50
Adblock Plus does not work for me. The main reason that you get one pop-up a week is because you probably don't go to alot of different websites. I get quite a few pop-ups during the day and I have yet to find an effective solution to this problem.
James Dalton
2007-07-28 11:35:54
It seems that the popup or popunders I have been getting also are being released with Javascript. maybe its time to switch to external pop up blocker since the internal one no longer works. Using firefox so long I have forgotten how pesky and annoying popups are.
2007-08-23 00:33:12
u should just remove fire fox when i had fire fox i got pop ups even when i wasnt surfing the net u should use microsoft internet explorer
2007-09-26 19:56:57
bob, the reason you were getting popups when you weren't surfing the net is due to adware on your system. I think IE has a lot more vulnerabilities than Firefox.
Asa Dotzler
2007-12-12 17:02:07
They're "evading" the Firefox pop-up blocker because you're actually "requesting" them. This new breed of pop-up and pop-under are triggered when you click whitespace on the webpage somewhere. Most people don't realize it, but they click around pages quite a bit while reading and sites are abusing that now.

There's no good way to distinguish between a window you wanted / requested with a click on a page and one you didn't want, but got by clicking on a page.

- A

2008-01-22 20:54:27
Bob - you said you get pop-ups even when you aren't browsing - sounds very strange, more like spyware - how/why did you attribute these to FF and not IE? I've had little luck with IE and FF has been pretty solid, hard to take your post seriously, considering most people I know won't touch IE with a ten foot mouse.
2008-02-08 09:27:05
What has been happening to me is that every day, the Block Popups check box in Firefox (under Tools>Options>Content) is somehow getting UNchecked! I redo it every day, but I have become sick of it. Does anyone know WHY this happens and HOW to fix it? I have seen others reporting the same complaint, but have yet to see a FIX to stop it from happening. Help, PLEASE!!!
2008-02-10 18:30:51
I can make it happen sure fire every time using a site called megaupload. when downloading a file say a Naruto episode for example the site will not let one download for 45 sceonds and after that one can get there file. along with clicking the download now bottun comes a pop_under for the site
Ann Teunissen
2008-02-26 21:43:03
Please delete your pop ups for all Stansberry Research articles this includes Stansberry Associates including customers service and . S.&A Report.oil

Urgent. Pleawse delete these pop ups. I need these publications

Thanks Ann Teunissen

not telling
2008-02-27 20:41:02
i think i might know how the pop ups r comein up on firefox it might be b/c someone hacked into firefox and made it so the pop up blocker don't see them
2008-03-29 18:26:56
after getting a virus i got these pop up basterds and i would use my rubber mallet to take em out when i finally got a shot they went away
2008-04-01 08:21:13
I have been having the same problem with popups lately does putting a theme on your firefox make a difference? i had a popup right now!
2008-04-08 13:29:46
Thank you jrs_66 for your fix/response dated 3/30/05. I followed your advice and it worked like a charm 3 years after your post! I'm running Firefox