How to Fix a Browser Hijack on Mozilla Firefox

Introduction

Browser hijacking or 'pop-up phishing' involves fraudulent messages that unexpectedly pop up for users when they are surfing the web. In many cases, cyber criminals infect otherwise legitimate websites with malicious code that causes these messages to appear when people visit them.
The content of these messages themselves is what makes them so effective. Often, they present the unsuspecting website visitor with some kind of fraudulent warning from a well-known reputable company, typically about the security of their computer. Then they either prompt the visitor to download some tool to fix the problem, such as an antivirus application which turns out to be malware itself, or to call a fraudulent phone number for "support." The abnormal behavior of the message itself and the inability to close or navigate away from them, makes the fraudulent messages appear to be somewhat credible.
This guide will demonstrate how to rid yourself of the worrisome pop-up message, and then perform some simple operations to get Mozilla Firefox back to normal.
Hijacked firefox

What About Pop-Ups?

This guide focuses on hijacked browsers. Pop-ups are another beast entirely and covered in another guide.

Preventing Pop-Ups in Firefox

1 OS Choice

There are 2 main Operating Systems for personal computers currently available, Windows and macOS.

Windows
Windows runs on computers produced by multiple companies, such as Lenovo, Asus, Dell, Toshiba, Hewlett Packard, Acer, and Sony.Windows 10
macOS
Apple is the only company that makes macOS computers.macOS Mojave

? What Operating System are you using?

  1. Windows
  2. macOS

We're here to help!

Connect to a Tech Pro

Call or chat with a Tech Pro 24/7.

Browser hijacking or 'pop-up phishing' involves fraudulent messages that unexpectedly pop up for users when they are surfing the web. In many cases, cyber criminals infect otherwise legitimate websites with malicious code that causes these messages to appear when people visit them.
The content of these messages themselves is what makes them so effective. Often, they present the unsuspecting website visitor with some kind of fraudulent warning from a well-known reputable company, typically about the security of their computer. Then they either prompt the visitor to download some tool to fix the problem, such as an antivirus application which turns out to be malware itself, or to call a fraudulent phone number for "support." The abnormal behavior of the message itself and the inability to close or navigate away from them, makes the fraudulent messages appear to be somewhat credible.
This guide will demonstrate how to rid yourself of the worrisome pop-up message, and then perform some simple operations to get Mozilla Firefox back to normal.
Hijacked firefox

What About Pop-Ups?

This guide focuses on hijacked browsers. Pop-ups are another beast entirely and covered in another guide.

Preventing Pop-Ups in Firefox

There are 2 main Operating Systems for personal computers currently available, Windows and macOS.

Windows
Windows runs on computers produced by multiple companies, such as Lenovo, Asus, Dell, Toshiba, Hewlett Packard, Acer, and Sony.Windows 10
macOS
Apple is the only company that makes macOS computers.macOS Mojave
The following steps can be used to terminate any browser, but the examples below will demonstrate using Internet Explorer.
  1. Open the Windows Task Manager.
    Using the Taskbar
    • Using your right mouse button, right-click on your Taskbar. Then select Task Manager from the menu.
      Mouse with Right Mouse Button highlighted.
      Taskbar right-click menu with Task Manager highlighted.
    Using a Keyboard Shortcut
    • On your keyboard use Ctrl+Shift+Esc.
      Keyboard with Ctrl Shift and Esc highlighted
    Using the Lock Screen
    • You can do Ctrl+Alt+Del on your keyboard, then click on Task Manager.
      PC Desktop Keyboard with Ctrl-Alt-Del highlighted.
      GINA Screen with Task Manager highlighted.
  2. Select your browser, then select End Task.
    Basic View
    Task Manager basic view with browser and End Task highlighted.
    Advanced View
    Task Manager advanced view with browser and End Task highlighted.
When you next open your browser, if you are asked to restore a session / pages, select No, or close the message.
  1. Open Mozilla Firefox.
    Mozilla Firefox Icon
  2. Click the Menu button in the top right of the screen.
    Menu button
  3. Click on Options.
    Options highlighted
  4. Click on Privacy & Security.
    Privacy & Security highlighted
  5. Click the Clear History button located under the History category.
    Clear History button highlighted
  6. Select the time range you wish to clear.
    Time range highlighted
  7. Click the Details button to expand them.
    Details expand button highlighted
  8. Choose the item categories you wish to clear.
    Item categories highlighted
    Setting Checkbox
    Browsing & Download History Checked

    Browsing History - While you browse Your browser will keep track of every page you visit, to try to make it easier to return. This can become corrupt due to modern active web pages.

    Download History - These are a list of files you've downloaded recently. It is entirely safe to delete, or keep this list, as it won't affect pages. Checking this option does not delete the files you've downloaded, just the list the browser keeps.

    Form & Search History Checked
    Information from entering forms online, such as your name, address, or other filled in information. This does not affect how a page loads, and can slow you down on your most commonly used pages.
    Cookies Checked
    Cookies are how websites 'know' you when you visit them multiple times. This file can become corrupt, and simply downloading a new one can fix many problems.
    You will have to log back into any pages you use, such as mail or social media.
    Active Logins Checked
    Active logins are sites that you are currently logged into that you have asked to remember that you are logged into. Clearing them just logs you out of these sites.
    Offline Website Data Unchecked
    If you've allowed it, a website can store files on your computer so that you can continue to use it when you are not connected to the Internet.
    Site Preferences Unchecked
    Site specific preferences, including the saved zoom level for sites, character encoding, and the permissions for sites.
     
  9. Click the Clear Now button.
    Clear Now button highlighted

Some browser extensions / addons can cause your browser to behave abnormally. Removing any unwanted, unnecessary, or unused browser extensions/addons can get your web browser running properly again.

Firefox icon

  1. Click on the three lines in the upper right hand corner.
    Firefox with 3 lines highlighted. Screenshot
  2. Click on Add-ons.
    Firefox menu with addons highlighted. Screenshot
  3. Click on Extensions on the left.
  4. The following steps can be repeated to remove multiple browser extensions.
    • Then click on Remove for the extension you want to remove.
      Extensions menu with Remove highlighted. Screenshot
      • If you accidentally removed something, click on Undo.
        Undo highlighted. Screenshot
    • You might get a new tab pop up upon removal, close the tab by hitting the X.
      Survey windows. Screenshot
      Browser Tab with X highlighted. Screenshot
  5. Extensions are now gone, you may have to restart your browser for it to take effect. If you removed a malicious extension, it might have changed your homepage.
  1. Open Firefox.
    Mozilla Firefox.
  2. Enter about:plugins into address bar and hit enter, then review your plug-ins and remove any that are malicious.
    Firefox plugins
  3. Enter about:addons into the address bar and hit enter, then click Extensions.
    Firefox extensions
  4. Review your extensions and determine if any are malicious. Remove those that are.
  5. Click the Menu button in the top right of the screen.
    Menu button
  6. Click Options.
    Firefox menu showing options selected
  7. Click Home. If you have a custom URL set verify it is not malicious.
    Firefox homepage settings
  8. Click the Start Menu.
    Windows 10 Start Menu.
  9. Search for Firefox and right-click the result.
  10. Select Open File Location
    Firefox right click menu within windows 10
  11. Right-click the Firefox shortcut and select Properties.
    Firefox right click menu
  12. Click the Shortcut tab and verify that the Target only contains the path "C:\Program Files (x86)\Mozilla Firefox\firefox.exe" with nothing after it. Click OK when done.
    Firefox shortcut properties
  13. Open Firefox and verify your homepage is correct.
  1. Open your browser and take note if it shows your normal home page or search page.
    Mozilla Firefox.
  2. Test your ability to search the web like you normally would.

Potentially Unwanted Programs (PUPs)

PUPs, or "Potentially unwanted programs," often arrive bundled with your computer, or tag along with another software program you meant to install, but were part of a EULA or "Recommended Offer" you probably clicked right through. These are programs that don't really do anything good for you. Some of these programs can add unwanted browser toolbars that clutter your browser, track your web browsing, show additional advertisements, or change your search page and other related settings.
Example of a PUP installing a search bar

You may need to remove an app or program because you need the space, simply don't need it anymore, or it is malicious. The following steps show you how to easily remove an app. The first method is exclusive to Windows 10, the second method will work with all Windows versions.

Windows 10 - Using Windows Settings
  1. Click Start (1), then click Settings (2).
    Windows start menu with the start button and settings highlighted.
  2. Next, Select Apps.
    Windows Settings with Apps highlighted.
  3. Scroll down and locate the app you wish to remove, and click on Uninstall.
    Apps screen with the uninstall option for an app highlighted.
  4. Carefully read any prompts in case there are special instructions. Proceed until the application is removed.
  5. Some applications may require that you reboot.
All Windows Versions - Using Control Panel
  1. On your keyboard push and release the Windows Key and R at the same time.
    PC Desktop Keyboard with Windows key and R highlighted.
  2. You will see a Run window open up. Type in appwiz.cpl then click on OK.
    Run windows with appwiz.cpl typed and OK highlighted. Screenshot
  3. Locate a program you wish to remove within the list, click once on it to highlight it, then click on Uninstall.
    Uninstall window with program and uninstall highlighted. Screenshot
  4. Carefully read any prompts in case there are special instructions. Proceed until the application is removed.
  5. Some applications may require that your computer be restarted to complete the uninstallation.
Before you restart or shut down your PC, make sure to save all necessary work to prevent data loss.
  1. Select the Start menu, then select Power.
    Windows 10 Start Menu
    Windows 10 Power Button
  2. Select Restart.
    Windows 10 Power menu with Restart highlighted.
  1. Open your browser and take note if it shows your normal home page or search page.
    • On a Desktop or Laptop, look for one of these icons:
      Main Desktop Browsers.
    • On a Smartphone or Tablet, look for one of these icons:
      Main Mobile Browsers.
  2. Make sure the page loads properly, and try following a few of the links from the page.
Unfortunately, your browser issue cannot be resolved via basic troubleshooting steps. Your machine will require hands-on service to determine the root cause of your issues.

Sometimes Chrome can get stuck as it launches. Forcing it to quit and restarting it usually fixes this problem.

  1. Select the Apple menu, then Force Quit.
    Apple menu with Force Quit highlighted.
  2. Highlight Firefox in the list, and select Force Quit.
    Force Quit with Firefox and Force Quit highlighted.
  3. You'll be prompted if you're sure, select Force Quit.
    Force quit prompt with Force Quit button highlighted.

Your web browser's homepage settings dictate the websites that are loaded when it is opened up.

Firefox icon

  1. Click on the three lines in the upper right hand corner.
    Firefox with 3 lines highlighted. Screenshot
  2. Click on Preferences.
    Firefox menu with Preferences highlighted. Screenshot
  3. Click on Home. If there is a custom URL you do not want, you can change it. When done you can close Firefox.
    Firefox Settings menu with Home and Custom URL highlighted. Screenshot

Some browser extensions / addons can cause your browser to behave abnormally. Removing any unwanted, unnecessary, or unused browser extensions/addons can get your web browser running properly again.

Firefox icon

  1. Click on the three lines in the upper right hand corner.
    Firefox with 3 lines highlighted. Screenshot
  2. Click on Add-ons.
    Firefox menu with addons highlighted. Screenshot
  3. Click on Extensions on the left.
  4. The following steps can be repeated to remove multiple browser extensions.
    • Then click on Remove for the extension you want to remove.
      Extensions menu with Remove highlighted. Screenshot
      • If you accidentally removed something, click on Undo.
        Undo highlighted. Screenshot
    • You might get a new tab pop up upon removal, close the tab by hitting the X.
      Survey windows. Screenshot
      Browser Tab with X highlighted. Screenshot
  5. Extensions are now gone, you may have to restart your browser for it to take effect. If you removed a malicious extension, it might have changed your homepage.
  1. Open Mozilla Firefox.
    Mozilla Firefox Icon
  2. Click the Menu button in the top right of the screen.
    Menu button
  3. Click on Options.
    Options highlighted
  4. Click on Privacy & Security.
    Privacy & Security highlighted
  5. Click the Clear History button located under the History category.
    Clear History button highlighted
  6. Select the time range you wish to clear.
    Time range highlighted
  7. Click the Details button to expand them.
    Details expand button highlighted
  8. Choose the item categories you wish to clear.
    Item categories highlighted
    Setting Checkbox
    Browsing & Download History Checked

    Browsing History - While you browse Your browser will keep track of every page you visit, to try to make it easier to return. This can become corrupt due to modern active web pages.

    Download History - These are a list of files you've downloaded recently. It is entirely safe to delete, or keep this list, as it won't affect pages. Checking this option does not delete the files you've downloaded, just the list the browser keeps.

    Form & Search History Checked
    Information from entering forms online, such as your name, address, or other filled in information. This does not affect how a page loads, and can slow you down on your most commonly used pages.
    Cookies Checked
    Cookies are how websites 'know' you when you visit them multiple times. This file can become corrupt, and simply downloading a new one can fix many problems.
    You will have to log back into any pages you use, such as mail or social media.
    Active Logins Checked
    Active logins are sites that you are currently logged into that you have asked to remember that you are logged into. Clearing them just logs you out of these sites.
    Offline Website Data Unchecked
    If you've allowed it, a website can store files on your computer so that you can continue to use it when you are not connected to the Internet.
    Site Preferences Unchecked
    Site specific preferences, including the saved zoom level for sites, character encoding, and the permissions for sites.
     
  9. Click the Clear Now button.
    Clear Now button highlighted
  1. Open your browser and take note if it shows your normal home page or search page.
    Mozilla Firefox.
  2. Test your ability to search the web like you normally would.

Potentially Unwanted Programs (PUPs)

PUPs, or "Potentially unwanted programs," often arrive bundled with your computer, or tag along with another software program you meant to install, but were part of a EULA or "Recommended Offer" you probably clicked right through. These are programs that don't really do anything good for you. Some of these programs can add unwanted browser toolbars that clutter your browser, track your web browsing, show additional advertisements, or change your search page and other related settings.
Example of a PUP installing a search bar

Removing an app may also remove all data for that app. Make sure you have any information you need backed up before removing an app for your Mac.

To Remove an App Installed from the App Store

  1. Open the Launchpad from the dock.
    Launchpad highlighted
  2. Click and hold on an icon until all icons start to jiggle.
    Shaking icon
  3. Click the "x" on the top left of the icon you want to remove.
    X highlighted
  4. Click Delete to confirm removal.
    Delete button highlighted

To Remove All Other Apps

  1. Open the Finder from the dock.
    Finder highlighted on the dock
  2. Click on Applications on the left.
    Application highlighted
  3. Drag the app you wish to remove to the trash can.
    Drag app to the trashcan
  4. Right click on the trashcan and click Empty Trash.
    Empty Trash highlighted
  1. From the menu bar across the top of the screen, select the Apple menu, then Restart...
    macOS Mojave Apple Menu with Restart highlighted.
  1. Open your browser and take note if it shows your normal home page or search page.
    • On a Desktop or Laptop, look for one of these icons:
      Main Desktop Browsers.
    • On a Smartphone or Tablet, look for one of these icons:
      Main Mobile Browsers.
  2. Make sure the page loads properly, and try following a few of the links from the page.
Unfortunately, your browser issue cannot be resolved via basic troubleshooting steps. Your machine will require hands-on service to determine the root cause of your issues.
We use cookies on our website to enhance your experience, analyze site usage and support our marketing efforts. To learn more, visit our Privacy Policy. By clicking “Accept”, you agree to our use of cookies and similar technologies.
Accept