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Troubleshoot Firefox issues caused by malware

Malware is short for "Malicious Software". It is a term generally used for software installed on your computer that is designed to infiltrate or damage a computer system without the owner's informed consent. Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of. This article describes what common symptoms are and how to prevent malware from being installed and get rid of them.

How do I know that my Firefox problem is a result of malware?

Symptoms are various and depend on the malware but if you have one or several of these behaviors, you may have malware installed on your computer.

How do I prevent malware from being installed?

There are simple rules to follow in order to prevent malware from being installed on your computer:

  • Keep your operating system and other software updated: Installation of malicious software usually takes advantage of known security vulnerabilities in other programs, which may have been patched in later versions. Make sure you are using the latest version of each piece of software you use, including plugins using Mozilla's plugincheck website and Windows using the Windows Update feature.
  • Don't install untrusted software: Some websites offer you software to accelerate your browser, to help you search the Web, to add toolbars that make things Firefox already does. Some unwanted programs also come bundled in software packages. Usually, these programs gather information on your browsing behavior that serve only people who designed them and interfere with Firefox. Make sure you install add-ons from Mozilla's add-on website and you uncheck unwanted programs in software wizards.
  • Don't click inside misleading pop-up windows: Many malicious websites try to install malware on your system by making images look like pop-up windows, or displaying an animation of the website scanning your computer. For more information on detecting a misleading pop-up, see Pop-up blocker settings, exceptions and troubleshooting.
  • Don't run a fake Firefox: Download Firefox from mozilla.org/firefox.
    Note: Please report misuse of the Firefox trademark in websites using the Mozilla's Violating Website Report page and in emails by forwarding them to Mozilla's abuse email.
  • Run anti-virus and anti-spyware real-time protection and scan your system periodically. Make sure your anti-virus and anti-spyware real-time protection is enabled. Scan your computer at least every month.

Mac security and malware protection

Mac systems tend to be regarded as more secure and, by default, more in control of available software, compared to Windows PCs. These Apple Support documents may be of help:

For information of a more technical nature, this Apple Support article discussion has a comprehensive summary of advice, recommendations and linked articles for Mac users:

How do I get rid of malware?

The Wikipedia article Linux malware has information and recommendations for Linux users.

How do I get rid of malware?

Recent Microsoft supported Windows is likely to have basic free anti-virus software built in or available free from Microsoft. If your anti-virus and anti-spyware software hasn't detected malware, scan your system with the free malware scanning programs listed below. You should scan with all programs because each program detects different malware and make sure that you update each program to get the latest version of their databases before doing a scan.

Warning: Anti-virus and anti-spyware software may sometimes generate false positives. Consider quarantining suspicious files rather than deleting them.
Note: Certain malware components can only be removed in Windows Safe ModeWindows Safe ModeWindows Safe ModeWindows Safe Mode.

Need more help?

You can ask for help in a forum specializing in malware removal, such as those listed below:

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Comments

See /forums/knowledge-base-articles/706675 for related discussion about this article.

See also: /forums/contributors/708073?page=3#post-45047 (re: "AdwCleaner" removal tool for Ask, Search, and Babylon toolbars)

A link to the Anti-rootkit utility, TDSSKiller, could be useful.

I just submitted my Review. Have been thinking about it for a few days.

Added the following scanning Programs for Windows:

  • Microsoft Security Essentials,
  • Spybot Search & Destroy,
  • Ad-Aware Free Internet Security
  • Kaspersky's Anti-rootkit utility TDSSKiller

Hopefully it will be approved.

I don't think this article must be an anti-malware software catalog.

Do we have evidences that these four new pieces of software detect malware that impacts Firefox and are not detected by the two current programs?

Rather than add more links to anti-malware scanners and applications, I would stick with the two applications already in the article and encourage people to get more help, if needed, from a forum specializing in malware removal.

In any case, I would not suggest Microsoft Security Essentials unless the person has no current real-time security software installed or wants to replace it. MSE is a real-time antivirus/anti-spyware program and recommends you first uninstall any existing real-time security software (see also this forum post which links to this installation checklist - see #3). If you were thinking to suggest a Microsoft on-demand scanner, the Microsoft Safety Scanner is linked from that forum post.

P.S. I deferred the pending revision.

AliceWyman said

In any case, I would not suggest Microsoft Security Essentials unless the person has no current real-time security software installed or wants to replace it. MSE is a real-time antivirus/anti-spyware program and recommends you first uninstall any existing real-time security software (see also this forum post which links to this installation checklist - see #3). If you were thinking to suggest a Microsoft on-demand scanner, the Microsoft Safety Scanner is linked from that forum post.

Sry i didn't knew much about MSE. I put it up because i thought it will be helpful for Windows users.

Microsoft Safety Scanner looks much better. I think Windows users would like to use a Microsoft security product as well.

scoobidiver said

Do we have evidences that these four new pieces of software detect malware that impacts Firefox and are not detected by the two current programs?

Hmm let see.

-> OK i haven't seen any user saying that their problem was resolved after using Spybot Search & Destroy. So you Remove it.

-> I distinctly remember seeing a Thread where the OP claimed that his problem was resolved after using Ad-Aware Free Internet Security but i don't really remember the Thread ID. So it will require some long digging to find-out if that's true.

-> As for Kaspersky's Anti-rootkit utility TDSSKiller, i started suggesting it after seeing it suggested by scoobidiver in a thread where the OP was having problems regarding Crashing or Hanging (will have to dig for it too). But after that, i suggested Kaspersky's Anti-rootkit utility TDSSKiller to users with Hanging and Crashing problems and i know that some of them were able to resolve their problems by using it (again will have to search a bit in My Contributed threads to find the actual Thread IDs).

AliceWyman said

P.S. I deferred the pending revision.

Thanks for that. It will give me some time to dig-out the evidence. Will post back later with the relevant Thread IDs.

scoobidiver, none of those threads you linked above show that BOTH Malwarebytes' Anti-Malware and SuperAntispyware Portable Scanner were tried and failed to find the malware.

I suppose it's OK to add Kaspersky's Anti-Rootkit Utility - TDSSKiller as a third tool in the arsenal but at some point we have to stop adding tools and encourage people to visit a malware removal forum for advanced help.

AliceWyman said

scoobidiver, none of those threads you linked above show that BOTH Malwarebytes' Anti-Malware and SuperAntispyware Portable Scanner were tried and failed to find the malware.
  • In the first thread, dormrod (not the OP) was the person who said that he ran TDSSKiller and it worked ... but he did not mention trying the two scanners in this article. (The quote in your your first point was actually from a different thread, /en-US/questions/860893 but I'll give you that, since the person there ran all the scanners then ran TDSSKILLER and said that it worked.)
  • The OP 80sPunkRockGirl in your second link did say '"I've run Malware Bytes Anti-Malware, Ad-Ware, AVG scans and Super Anti Spyware (not SuperAntispyware Portable Scanner) so I'll give you that, since she then ran TDSSKiller and it worked.
  • In your third link, the quote was from the OP but the person who said that he ran TDSSKiller and it worked was dhoang (not the OP) and he never mentioned running the other scanners.
  • In your fourth link, the quote was from AnonymousUser but the person who said that he ran TDSSKiller and it worked was rhines (not the OP) and he never mentioned running the other scanners.

In any case, I said before, I suppose it's OK to add Kaspersky's Anti-Rootkit Utility - TDSSKiller as a third tool in the arsenal.

I approved your revision to add Kaspersky's utility to the article.

I opened a detailed thread in the Contributors Forum -> https://support.mozilla.org/en-US/forums/contributors/708420

I added Microsoft Safety Scanner, reordered the list of malware scanners and changed the MalwareBytes' link to the free version, as follows:

  1. Related discussion on adding Microsoft Safety Scanner as a malware removal tool is at https://support.mozilla.org/forums/contributors/708895#post-50141
  2. Malwarebytes' Anti-Malware Free is linked from the new article, Firefox 18 crashes on startup due to malware - how to fix so I used the same link. The current Malwarebytes' Anti-Malware link redirects to http://www.malwarebytes.org/products/malwarebytes_pro/
  3. AdwCleaner was added to the list in this revision, which was approved Nov 15, 2012 (with no discussion). I don't really agree with adding AdwCleaner since the documentation is in French .... but I wouldn't remove it without discussion so I moved it to the bottom of the list.

I made a minor edit to update the TDSSKiller link, which was http://support.kaspersky.com/faq/?qid=208283363 ... since that link redirects me to http://support.kaspersky.com/viruses/disinfection/5350

This came up in /forums/knowledge-base-articles/710471

I am not Mac user, so advice from others is needed please.

It seems there is a Malwarbytes product available since July 2015 for Mac s. Malwarebytes is reputable and we already include mention of their anti malware product for Windows. So it seems sensible to include

We link to this Article, which was apparently last updated in 2013

Is there anything more up to date ?

I note the article mentions Clam repeatedly. Apparently ClamXav is included in Mac OS X server from version 10.4. and that would have been freeware, but is now commercial. There will still be the command line version of Clam available. See for instance https://en.wikipedia.org/wiki/Clam_AntiVirus

Hi, John.

I agree we should replace the link to the outdated "Harden your Mac against malware attacks" article with something more current ... maybe one or both of these articles?

https://support.apple.com/en-us/HT201940 About the "Are you sure you want to open it?" alert (File Quarantine / Known Malware Detection) in OS X

https://support.apple.com/kb/PH21768 OS X El Capitan: Protect your Mac from malware


I see you posted a question about the Harden your Mac against malware attacks article to the apple discussion forums:

https://discussions.apple.com/message/29938056#29938056 Update to Article: Harden your Mac against malware attacks

You've gotten a number of answers to your post, including a lengthy reply, https://discussions.apple.com/message/29938930#29938930 ... which says, in part:

Starting with OS X 10.8.3, a third layer of protection has been added: a "Malware Removal Tool" (MRT). MRT runs automatically in the background. It checks for, and removes, malware that matches a recognition database maintained by Apple.

I would not link to Malwarebytes Anti-Malware for Mac since it may encourage Mac users to install unneeded software. From what I've gathered, current OS X versions already include built-on malware protection, including a removal tool since OS X 10.8.3 according to the forum reply I referenced above.

For the record, my iMac is running an older version of OS X (10.6.8) so I'm not the best person to update this article. I'll set up a "Needs change" entry.

Thanks Alice, I knew you use a Mac & hoped you would help.

My thoughts about the antimalware tool were more as a method of removal of adware as we do in Windows.

As it stands the only advice Mac users see on getting rid of malware is the Hardening Macs link. That Apple article besides being out of date also did not really offer advice on getting rid of malware. (The update discussion does mention removal tools).

Macs are obviously not always immune to adware issues & browser hijacks despite the built in protection.

Possibly MRT was not actually turned on in some cases. The full comment was

4. Starting with OS X 10.8.3, a third layer of protection has been added: a "Malware Removal Tool" (MRT). MRT runs automatically in the background. It checks for, and removes, malware that matches a recognition database maintained by Apple. To ensure that MRT will run when that database is updated, open the App Store pane in System Preferences and check the box marked Install system data files and security updates if it's not already checked. Like XProtect, MRT is effective against known threats, but not against unknown ones. It notifies you if it finds malware, but otherwise it has no user interface.

OR maybe it is just a case of lots of what to us are browser hijacks or Adware are potentially something some users consider legitimate. Thats why Windows users in addition to using AV may need to use adware removal tools.

It seems likely Clam is redundant, being most likely to be of use in protecting others from MS malware than being of help to the ordinary Mac User

I like both the articles 1, 2 you found. Short & simple user facing type documents. I also like very much the reply that I received3 that you mentioned.

I now have a pending edit. I've added all three links. l also added a note about Windows MS. I make no mention of clam, or malwarebytes in relation to Macs. I added an extra section as we are not realy adding information about removing malware.

The MS note was because we get endless issues on the forum with problems from security related software, mainly the bundled software, and so I think we should use all opportunities possible that help users understand that a lot of the problem software is not actually essential.

At least with such a revision we have more comprehensive and up to date information made available. Possibly we could add user friendly tips or information on Macs settings or expand malware removal advice on Macs but I need to rely on a Mac user to sort that out properly

John, Nice revision!

I made a few edits to your revision since I wasn't sure if you meant to show the "How do I get rid of Malware?" section for Mac. Can you review?

John, thanks for approving my revision. I marked it ready to localize and I removed the "Needs change" entry.