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Windows Defender Alert Scam

Also Known As: "Windows Defender Alert" virus
Type: Adware
Damage level: Medium

What is Windows Defender Alert?

"Windows Defender Alert" is a fake error message displayed by a malicious website. Many users visit this website inadvertently - they are redirected by various rogue applications that stealthily infiltrate systems during installation of regular software (the "bundling" method).

As well as causing redirects, these potentially unwanted programs (PUPs) deliver intrusive online advertisements and continually track users' Internet browsing activity.

Windows Defender Alert adware

The "Windows Defender Alert" error states that the system has been infected with the Zeus virus and that private information (logins/passwords, banking information, local files, etc.) is at risk. It states that the virus must be removed immediately and victims are encouraged to contact "Microsoft Technical Support" via a toll-free telephone number ("(888) 252-1520") provided. 

They will then supposedly receive help in removing the malware. Be aware, however, that the "Windows Defender Alert" error is fake - there is no infection. Cyber criminals generate revenue by tricking victims into calling and paying for services that are not required.

Therefore, you should never attempt to call the aforementioned telephone number. This error message can be removed simply by closing the web browser. As mentioned above, PUPs also deliver various advertisements. To achieve this, developers employ a "virtual layer" - a tool that enables placement of third party graphical content on any site.

Therefore, the ads often conceal underlying content, significantly diminishing the Internet browsing experience. Furthermore, some lead to malicious websites - clicking them risks further computer infections.

In addition, PUPs continually record various user-system information (for example, location, Internet Protocol addresses, Internet Service Providers, website URLs visited, pages viewed, search queries, mouse/keyboard activity, etc.) that might contain personal details.

This data is shared with third parties (potentially, cyber criminals) who misuse personal details to generate revenue. Therefore, information tracking can result in serious privacy issues or even identity theft. PUPs should be uninstalled immediately.

Threat Summary:
Name "Windows Defender Alert" virus
Threat Type Adware, Unwanted ads, Pop-up Virus
Symptoms Seeing advertisements not originating from the sites you are browsing. Intrusive pop-up ads. Decreased Internet browsing speed.
Distribution methods Deceptive pop-up ads, free software installers (bundling), fake flash player installers.
Damage Decreased computer performance, browser tracking - privacy issues, possible additional malware infections.
Malware Removal (Windows)

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There are dozens of fake error messages similar to "Windows Defender Alert". The list of examples includes (but is not limited to) Microsoft Warning Alert, Login Security Alert, Your Computer Is In Blocked State, and Microsoft Help Desk

All of these errors claim that system is infected or damaged in some way, however, these are merely attempts to scare and trick victims into buying 'customer support'. None of these error messages should be trusted - they are designed only to generate revenue for the developers.

PUPs also have an identical purpose: to generate revenue. By offering various 'useful features', they attempt to give the impression of legitimacy, however, they merely cause unwanted redirects, deliver intrusive ads, and collect various user-system information.

How did adware install on my computer?

As mentioned above, PUPs are distributed using the bundling method - stealth installation of third party programs with regular software/apps. Developers know that users often rush the download/installation processes and skip steps. Therefore, bundled PUPs are hidden within the "Custom/Advanced" settings.

By carelessly skipping this section, users expose their systems to risk of various infections and compromise their privacy.

How to avoid installation of potentially unwanted applications?

To prevent system infiltration by PUPs, be very cautious when downloading and installing software. Closely analyze each step using the "Custom/Advanced" settings and opt-out of all third party applications listed for download/installation. Bundled software should never be installed.

Screenshot of "Windows Defender Alert" scam pop-up:

Windows Defender Alert fake error

Text presented within this pop-up:

Windows Defender Alert: Zeus Virus Detected in Your Computer!
Please do Not Shut Down or Reset Your Computer.
The following data will be compromised if your continue:
1. Passwords
2. Browser History
3. Credit Card Information
4. Local Hard Disk Files.
The virus is well known for complete identity and credit card theft. Further action through this computer or any computer on the network will reveal private information and involve serious risks.
Call Microsoft Technical Department (Toll Free): (888) 252-1520

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Quick menu:

Adware removal:

Windows 11 users:

Accessing Apps and Features in Windows 11

Right-click on the Start icon, select Apps and Features. In the opened window search for the application you want to uninstall, after locating it, click on the three vertical dots and select Uninstall.

Windows 10 users:

Accessing Programs and Features (uninstall) in Windows 8

Right-click in the lower left corner of the screen, in the Quick Access Menu select Control Panel. In the opened window choose Programs and Features.

Windows 7 users:

Accessing Programs and Features (uninstall) in Windows 7

Click Start (Windows Logo at the bottom left corner of your desktop), choose Control Panel. Locate Programs and click Uninstall a program.

macOS (OSX) users:

Uninstall app in OSX (Mac)

Click Finder, in the opened screen select Applications. Drag the app from the Applications folder to the Trash (located in your Dock), then right click the Trash icon and select Empty Trash.

Windows Defender Alert adware uninstall via Control Panel

In the uninstall programs window, look for any suspicious/recently-installed applications, select these entries and click "Uninstall" or "Remove".

After uninstalling the potentially unwanted program, scan your computer for any remaining unwanted components or possible malware infections. To scan your computer, use recommended malware removal software.

Remove adware from Internet browsers:

Video showing how to remove potentially unwanted browser add-ons:

Internet Explorer logoRemove malicious add-ons from Internet Explorer:

Removing Windows Defender Alert ads from Internet Explorer step 1

Click the "gear" icon Internet Explorer options icon (at the top right corner of Internet Explorer), select "Manage Add-ons". Look for any recently-installed suspicious browser extensions, select these entries and click "Remove".

Removing Windows Defender Alert ads from Internet Explorer step 2

Optional method:

If you continue to have problems with removal of the "windows defender alert" virus, reset your Internet Explorer settings to default.

Windows XP users: Click Start, click Run, in the opened window type inetcpl.cpl In the opened window click the Advanced tab, then click Reset.

Resetting Internet Explorer settings to default on Windows XP

Windows Vista and Windows 7 users: Click the Windows logo, in the start search box type inetcpl.cpl and click enter. In the opened window click the Advanced tab, then click Reset.

Resetting Internet Explorer settings to default on Windows 7

Windows 8 users: Open Internet Explorer and click the gear icon. Select Internet Options.

Reseting Internet Explorer settings to default in Windows 8 - accessing

In the opened window, select the Advanced tab.

Resetting Internet Explorer settings to default on Windows 8 - Internet options advanced tab

Click the Reset button.

Resetting Internet Explorer settings to default on Windows 8 - click the Reset button in the Internet options advanced tab

Confirm that you wish to reset Internet Explorer settings to default by clicking the Reset button.

Resetting Internet Explorer settings to default on Windows 8 - confirm settings reset to default by clicking the reset button

Google Chrome logoRemove malicious extensions from Google Chrome:

Removing Windows Defender Alert  ads from Google Chrome step 1

Click the Chrome menu icon Google Chrome options icon (at the top right corner of Google Chrome), select "Tools" and click "Extensions". Locate all recently-installed suspicious browser add-ons, select these entries and click the trash can icon.

Removing Windows Defender Alert ads from Google Chrome step 2

Optional method:

If you continue to have problems with removal of the "windows defender alert" virus, reset your Google Chrome browser settings. Click the Chrome menu icon Google Chrome menu icon (at the top right corner of Google Chrome) and select Settings. Scroll down to the bottom of the screen. Click the Advanced… link.

Google Chrome settings reset step 1

After scrolling to the bottom of the screen, click the Reset (Restore settings to their original defaults) button.

Google Chrome settings reset step 2

In the opened window, confirm that you wish to reset Google Chrome settings to default by clicking the Reset button.

Google Chrome settings reset step 3

Mozilla Firefox logoRemove malicious plug-ins from Mozilla Firefox:

Removing Windows Defender Alert ads from Mozilla Firefox step 1

Click the Firefox menu firefox menu icon (at the top right corner of the main window), select "Add-ons". Click "Extensions", in the opened window, remove all recently-installed suspicious browser plug-ins.

Removing Windows Defender Alert ads from Mozilla Firefox step 2

Optional method:

Computer users who have problems with "windows defender alert" virus removal can reset their Mozilla Firefox settings.

Open Mozilla Firefox, at the top right corner of the main window, click the Firefox menu, firefox menu icon in the opened menu, click Help.

Accessing settings (Reset Firefox to default settings step 1)

Select Troubleshooting Information.

Accessing Troubleshooting Information (Reset Firefox to default settings step 2)

In the opened window, click the Refresh Firefox button.

Clicking on Refresh Firefox button (Reset Firefox to default settings step 3)

In the opened window, confirm that you wish to reset Mozilla Firefox settings to default by clicking the Refresh Firefox button.

Confirm your want to reset Firefox settings to default (Reset Firefox to default settings step 4)

safari browser logoRemove malicious extensions from Safari:

removing adware from safari step 1 - accessing preferences

Make sure your Safari browser is active, click Safari menu, and select Preferences....

removing adware from safari step 2 - removing extensions

In the opened window click Extensions, locate any recently installed suspicious extension, select it and click Uninstall.

Optional method:

Make sure your Safari browser is active and click on Safari menu. From the drop down menu select Clear History and Website Data...

resetting safari step 1

In the opened window select all history and click the Clear History button.

resetting safari step 2

Microsoft Edge (Chromium) logoRemove malicious extensions from Microsoft Edge:

Removing adware from Microsoft Edge step 1

Click the Edge menu icon Microsoft Edge (chromium) menu icon (at the upper-right corner of Microsoft Edge), select "Extensions". Locate all recently-installed suspicious browser add-ons and click "Remove" below their names.

Removing adware from Microsoft Edge step 2

Optional method:

If you continue to have problems with removal of the "windows defender alert" virus, reset your Microsoft Edge browser settings. Click the Edge menu icon Microsoft Edge (chromium) menu icon (at the top right corner of Microsoft Edge) and select Settings.

Microsoft Edge (Chromium) reset step 1

In the opened settings menu select Reset settings.

Microsoft Edge (Chromium) reset step 2

Select Restore settings to their default values. In the opened window, confirm that you wish to reset Microsoft Edge settings to default by clicking the Reset button.

Microsoft Edge (Chromium) reset step 3

  • If this did not help, follow these alternative instructions explaining how to reset the Microsoft Edge browser.

Summary:

declining installation of adware while downloading free software sampleCommonly, adware or potentially unwanted applications infiltrate Internet browsers through free software downloads. Note that the safest source for downloading free software is via developers' websites only. To avoid installation of adware, be very attentive when downloading and installing free software. When installing previously-downloaded free programs, choose the custom or advanced installation options – this step will reveal any potentially unwanted applications listed for installation together with your chosen free program.

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About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for pcrisk.com since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Malware activity

Global malware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

QR Code
Windows Defender Alert virus QR code
Scan this QR code to have an easy access removal guide of "Windows Defender Alert" virus on your mobile device.
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