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Possible adware/malware when downloading Firefox?

  • 7 replies
  • 3 have this problem
  • Last reply by James

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I recently switched from Chrome to Firefox and already, I have had problems. I downloaded Firefox and opened it when the download was finished and tried to sign into my Google account, when a lot of random adverts appeard, and my anti-virus popped up blocking whatever it was. At this point I was really concerned as I had just completed a full system scan before changing browsers, and the scan was clean. I then looked at the Add-Ons, which I found two that I had never heard of. I'm not sure whether they were on my computer already or had been added as I downloaded Firefox. I'm confused as I have never seen the two Add-Ons before, not even in Chrome.

Both Add-Ons are disabled and deleted and as far as I'm aware, everything is running as it should be. However, I would like to know if anyone else has experienced this problem before, and if so, what should be done about it. I'm usually very careful when online, so I really don't know where these Add-Ons came from, or if they could be harmful.

Any help with this would be great!

Modified by MollyBrown

All Replies (7)

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Hi Molly, Sorry you are having problems.

It would be stupid to claim Mozilla Firefox servers, or its Content Distribution Network could never be hacked. But is it exceedingly unlikely any malware or adware came from a Mozilla Firefox download IF you used an official site such as

Unofficial sites are likely to bundle & offer all sorts of unwanted software, & may not even provide a genuine and up to date Firefox. Some sites will even be sources of malware or hoaxes.

As an example of Mozilla's thinking on security have a look at this blog

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Hi John,

I can assure you that I did download Firefox from Mozilla's official website, I have not visited or downloaded anything from the links you suggested above.

The situation is a little confusing because I expected Firefox to only have my anti-virus Add-Ons and nothing else. I really cannot think of where the other two Add-Ons came from, I just started to recieve adverts at random, a couple which opened automatically in another window.

I ran both Malwarebytes and my anti-virus again just to double check if it was stored on my computer, but the scan came up with nothing.

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I suppose there were many places where you could have picked up the add-ons. It is very unlikely to have been from Mozilla, but many things are thought to be impossible until someone proves otherwise.

If you feel it was from Mozilla, try downloading and installing Firefox again, carefully recording which site you visit, and save & retain the installer file.

Firefox may recognise and list plugins that are already on your computer. Firefox may also pick up malware or adware that is already on your computer. Some adware may not be detected by Malwarebytes or your AV because strictly it is not classified as a virus, and not really Malware.

Some people actually intentionally install adware, or what many consider foistware or unwanted programs. Try scanning with other tools especially AdwCleaner Here's a list

You mention AV add-ons. Often any add-ons associated with AV software are of rather speculative benefit. Firefox already has some built in Phishing and Malware protection.

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What are these two unnamed Addons or rather Extensions you have not heard off?

The only thing That Firefox has come with in last while is the OpeH264 video Codec that can be seen in Plugins section.

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I can't actually remember the names of the Add-ons/extensions so I apologise for that. I decided at the time that it would be best to remove them ASAP as I didn't know what they were.

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I have an issue installing from official site also. Before the installation downloaded file can run I get that the file was deleted because it has a virus

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WhyWHyWhy said

I have an issue installing from official site also. Before the installation downloaded file can run I get that the file was deleted because it has a virus

Try the full setup as some antivirus clients still occasionally give false positive on the stub installer even though the stub installer has existed since Firefox 18.0