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, which 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.

• Some ad popups display all the time, even though you've blocked popups. For more information on blocking popups, see Pop-up blocker settings, exceptions and troubleshooting.
• Your searches are redirected to another site in order to feed you content from that website and you are being disallowed from blocking them. For more information, see What to do when searches take you to the wrong search website.
• Your home page has been hijacked. For more information on setting your home page, see How to set the home page.
• Firefox never finishes loading or can't load certain websites. For more information, see Websites show a spinning wheel and never finish loading and Firefox cannot load certain websites.
• Firefox crashes or hangs a lot. For more information, see Troubleshoot Firefox crashes (closing or quitting unexpectedly) and Firefox hangs or is not responding - How to fix.
• Firefox does not start. For more information, see Firefox won't start - find solutions.
• Problems with connecting to Facebook. For more information on problems with Facebook, see Fix problems with Facebook games, chat and more.
• Firefox keeps opening many tabs or windows. For more information, see Firefox repeatedly opens empty tabs or windows after you click on a link.
• Unwanted toolbars have been installed. For more information on customizing Firefox, see Remove a toolbar that has taken over your Firefox search or home page and How to remove the Babylon toolbar, home page and search engine.
• The malware may have loaded modules into Firefox. These modules are displayed on the Firefox about:third-party page. For more information, see Identify problems caused by third-party modules in Firefox for Windows.

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 all software you use, either by enabling the software's automatic update feature, if available, or by checking for updates from the software provider and by 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 or 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 the 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. Check to see if you have unwanted add-ons and disable or remove them.
• 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.

Need more help?

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

• Bleeping Computer Forums
• Malwarebytes Forums
• SWI Forums