This article has been created to explain what is the Critical Firefox Update virus and how to stop such malicious redirects to dangerous pages in the future.
A new redirect web page which tries to infect victim computers with malware via JavaScript file, called firefox-patch.js. The redirect page aims to convince users that they should immediately update their version of Firefox and display a pop-up which automatically shows a prompt to save the patch file or automatically open it. The JavaScript file itself is reported by security researchers to be a well-known Trojan Horse infection, going by the name Kovter, which was reported mainly to be associated with such fake updates as a mean of distribution. If you believe that your computer has been infected by the Kovter Trojan or if you keep seeing the “Critical Firefox Update” screen appearing, we recommend that you read the following article as it aims to help you secure your computer.
Threat Summary
| Name | Critical Firefox Update (Kovter Malware) |
| Type | Trojan |
| Short Description | Displayed by a fake web page, the Kovter trojan aims to steal information from the infected computers. |
| Symptoms | Your web browser may display a web-page , headed “Critical Firefox Update”. It asks you to download a .js file, which is the malware infection module. |
| Distribution Method | Via a fake Firefox Update page. |
| Detection Tool |
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User Experience | Join Our Forum to Discuss Critical Firefox Update (Kovter Malware). |
Critical Firefox Update Page – Distribution Methods
In order for you, the user to see it, the Critical Firefox Update page may be spread as a result of either visiting a web page, which causes a redirect to it or as a result of having adware or a similar unwanted program on your computer.
If it infects your computer as a result of a web page, then be advised that this page is either malicious or a compromised legitimate one. It often happens that cyber-criminals tend to intercept traffic from legitimate web pages to display their redirects and infect victims and they often target sites with bad security practices.
If however you see all sorts of redirects and pop-ups of such type, then it is very likely that you may have started seeing this web page as a result of having a PUP (potentially unwanted program) that is install on your OS. These types of PUPs often pretend to be legitimate helper programs, but their main goal is to display ads that generate money to their developers via suspicious pay-per-click schemes.
Critical Firefox Update and Kovter Trojan – More Information
When you see the Critical Firefox Update page, you may immediately notice a pop-up alongside it, asking you to download firefox-patch.js:
This .js file is the infection file of the Kovter Trojan horse. The Kovter Trojan is a threat that exists since the first appearances of the Police type of ransomare viruses. The virus has evolved in a more sophisticated variant since then that injects a JavaScript code onto victims computers.
When an infection with Kovter malware commences, the virus first triggers a dropper which drops malicious files in %AppData% and %Local% directories. This activity results in the Kovter malware being able to create a registry entry that triggers a maicious shell code in Widnows PowerShell and causes a restart, sealing it’s infectionas successful. The outcome of this after Kovter restarts is a file, called regsvr32.exe or similar fake Windows process name to run with administrative priveleges on the infected machine.
The outcome of this is that Kovter is capable to perform the following activities on a compromised computer:
- Display advertisements and connect the victim PC to various third-party hosts.
- Take screenshots on the compromised machine.
- Obtain passwords.
- Steal files from the computer it has infected.
- Record sound or video from the camera and microphone.
- Log the keystrokes you type.
Remove Critical Firefox Update and Kovter Troaj from Windows
If you want to remove the Kovter Trojan from Windows, we strongly suggest that you follow the removal instructions underneath this article. They have been divided in manual as well as automatic removal instructions with their main goal being to help you remove this virus according to your personal experience and preferences, concerning malware removal. Furthermore, if manual removal does not seem to be helpful, an automatic removal is also strongly advisable. According to security experts, the most effective method for automatic removal is to download and run a scan using an advanced anti-malware software. It will help you to automatically remove the Kovter malware and the software that may be causing such redirections to appear on your PC and also ensure that future protection is also available.
Ventsislav Krastev
Ventsislav is a cybersecurity expert at SensorsTechForum since 2015. He has been researching, covering, helping victims with the latest malware infections plus testing and reviewing software and the newest tech developments. Having graduated Marketing as well, Ventsislav also has passion for learning new shifts and innovations in cybersecurity that become game changers. After studying Value Chain Management, Network Administration and Computer Administration of System Applications, he found his true calling within the cybersecrurity industry and is a strong believer in the education of every user towards online safety and security.
Follow Me:
- Guide 1: How to Remove Critical Firefox Update (Kovter Malware) from Windows.
- Guide 2: Get rid of Critical Firefox Update (Kovter Malware) from Mac OS X.
- Guide 3: Remove Critical Firefox Update (Kovter Malware) from Google Chrome.
- Guide 4: Erase Critical Firefox Update (Kovter Malware) from Mozilla Firefox.
- Guide 5: Uninstall Critical Firefox Update (Kovter Malware) from Microsoft Edge.
- Guide 6: Remove Critical Firefox Update (Kovter Malware) from Safari.
- Guide 7: Eliminate Critical Firefox Update (Kovter Malware) from Internet Explorer.
Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer
How to Remove Critical Firefox Update (Kovter Malware) from Windows.
Step 1: Boot Your PC In Safe Mode to isolate and remove Critical Firefox Update (Kovter Malware)
Step 2: Uninstall Critical Firefox Update (Kovter Malware) and related software from Windows
Here is a method in few easy steps that should be able to uninstall most programs. No matter if you are using Windows 10, 8, 7, Vista or XP, those steps will get the job done. Dragging the program or its folder to the recycle bin can be a very bad decision. If you do that, bits and pieces of the program are left behind, and that can lead to unstable work of your PC, errors with the file type associations and other unpleasant activities. The proper way to get a program off your computer is to Uninstall it. To do that:
Follow the instructions above and you will successfully uninstall most programs.
Step 3: Clean any registries, created by Critical Firefox Update (Kovter Malware) on your computer.
The usually targeted registries of Windows machines are the following:
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
- HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
- HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
You can access them by opening the Windows registry editor and deleting any values, created by Critical Firefox Update (Kovter Malware) there. This can happen by following the steps underneath:
Tip: To find a virus-created value, you can right-click on it and click "Modify" to see which file it is set to run. If this is the virus file location, remove the value.
Before starting "Step 4", please boot back into Normal mode, in case you are currently in Safe Mode.
This will enable you to install and use SpyHunter 5 successfully.
Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer
Get rid of Critical Firefox Update (Kovter Malware) from Mac OS X.
Step 1: Uninstall Critical Firefox Update (Kovter Malware) and remove related files and objects
1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:
- Go to Finder.
- In the search bar type the name of the app that you want to remove.
- Above the search bar change the two drop down menus to “System Files” and “Are Included” so that you can see all of the files associated with the application you want to remove. Bear in mind that some of the files may not be related to the app so be very careful which files you delete.
- If all of the files are related, hold the ⌘+A buttons to select them and then drive them to “Trash”.
In case you cannot remove Critical Firefox Update (Kovter Malware) via Step 1 above:
In case you cannot find the virus files and objects in your Applications or other places we have shown above, you can manually look for them in the Libraries of your Mac. But before doing this, please read the disclaimer below:
You can repeat the same procedure with the following other Library directories:
→ ~/Library/LaunchAgents
/Library/LaunchDaemons
Tip: ~ is there on purpose, because it leads to more LaunchAgents.
Step 2: Scan for and remove Critical Firefox Update (Kovter Malware) files from your Mac
When you are facing problems on your Mac as a result of unwanted scripts and programs such as Critical Firefox Update (Kovter Malware), the recommended way of eliminating the threat is by using an anti-malware program. SpyHunter for Mac offers advanced security features along with other modules that will improve your Mac’s security and protect it in the future.
Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer
Remove Critical Firefox Update (Kovter Malware) from Google Chrome.
Step 1: Start Google Chrome and open the drop menu
Step 2: Move the cursor over "Tools" and then from the extended menu choose "Extensions"
Step 3: From the opened "Extensions" menu locate the unwanted extension and click on its "Remove" button.
Step 4: After the extension is removed, restart Google Chrome by closing it from the red "X" button at the top right corner and start it again.
Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer
Erase Critical Firefox Update (Kovter Malware) from Mozilla Firefox.
Step 1: Start Mozilla Firefox. Open the menu window
Step 2: Select the "Add-ons" icon from the menu.
Step 3: Select the unwanted extension and click "Remove"
Step 4: After the extension is removed, restart Mozilla Firefox by closing it from the red "X" button at the top right corner and start it again.
Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer
Uninstall Critical Firefox Update (Kovter Malware) from Microsoft Edge.
Step 1: Start Edge browser.
Step 2: Open the drop menu by clicking on the icon at the top right corner.
Step 3: From the drop menu select "Extensions".
Step 4: Choose the suspected malicious extension you want to remove and then click on the gear icon.
Step 5: Remove the malicious extension by scrolling down and then clicking on Uninstall.
Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer
Remove Critical Firefox Update (Kovter Malware) from Safari.
Step 1: Start the Safari app.
Step 2: After hovering your mouse cursor to the top of the screen, click on the Safari text to open its drop down menu.
Step 3: From the menu, click on "Preferences".
Step 4: After that, select the 'Extensions' Tab.
Step 5: Click once on the extension you want to remove.
Step 6: Click 'Uninstall'.
A pop-up window will appear asking for confirmation to uninstall the extension. Select 'Uninstall' again, and the Critical Firefox Update (Kovter Malware) will be removed.
Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer
Eliminate Critical Firefox Update (Kovter Malware) from Internet Explorer.
Step 1: Start Internet Explorer.
Step 2: Click on the gear icon labeled 'Tools' to open the drop menu and select 'Manage Add-ons'
Step 3: In the 'Manage Add-ons' window.
Step 4: Select the extension you want to remove and then click 'Disable'. A pop-up window will appear to inform you that you are about to disable the selected extension, and some more add-ons might be disabled as well. Leave all the boxes checked, and click 'Disable'.
Step 5: After the unwanted extension has been removed, restart Internet Explorer by closing it from the red 'X' button located at the top right corner and start it again.
