How to remove Windows Defender security warning scam

The Windows Defender security warning scam – those fake pop-ups claiming your PC is infected – tricks users into calling scammers or downloading malware. In 2026, it continues to spread via malicious ads, phishing links, or drive-by downloads on shady websites.

I’ve tested removal methods on real infected systems across major browsers to confirm these steps work reliably. In this guide, I’ll walk you through how to remove Windows Defender security warning scams and share proven tips to help you block future attacks and keep your device secure.

What is the Windows Defender security warning?

Windows Defender security warning is a type of scareware or a phishing scam.

It redirects you to a page that looks like the official Microsoft website, even though its URL suggests otherwise. The page displays a message stating that your computer has been infected with malware (Trojan, for example) and that you need to contact a customer support agent by phone so that they can resolve the issue.

One thing you should know about the Windows Defender security warning is that it appears to be a legitimate message from Windows, which is why it’s so dangerous – many users might not even double-check and try to Google it.

It is a common tactic of scammers, making a pop-up look as legitimate as possible so that people would not suspect anything bad.

In any case, the telephone number is most likely to direct you to a scam call center where an agent will either try to infect your computer with malware, steal your personal information, or demand you pay money for fake services.

Name	Windows Defender/Security Warning message
Type	Scam, social engineering, fraud
Devices	Any device with a web browser, but Windows devices are more targeted
Symptoms	Fake error messages, fake warnings, pop-up errors, fake scans
Damage	Loss of sensitive information, identity theft, monetary loss, possible further infections

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Why am I seeing the Windows Defender security warning?

There could be a few different reasons why you’re seeing the Windows Defender security warning. Here are some of the possible ones:

• You visited a compromised website that redirected you to the scam page
• You clicked an ad that redirected you to the fake website
• You have malicious adware installed on your device

In any case, simply closing the window might not solve the problem, as, once it appears, the pop-up message might show up every single time you open your browser.

How to remove Windows Defender security warning pop-ups

As the Windows Defender security warning is browser-based, most of the steps you should take to get rid of it are also related to your browser. Here are the possible measures you can take to make the warning disappear:

1. Force close and reopen your browser
2. If you still get redirected to the scam page, reset the browser’s settings (more instructions below), or completely reinstall the browser
3. If this still occurs, you might have adware or some kind of a PUP (potentially unwanted program) installed on your computer, and need to remove it

If you are unsure which of the installed apps is causing this behavior, an antivirus program (like TotalAV) can detect and remove it from your computer.

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Remove Windows Defender security warning from your browser

Resetting the browser settings is one of the first things you should do if you want to get rid of the Windows Defender Security warning scam. Below you will find the instructions on how to do it on different browsers.

Remove Windows Defender pop-up from Chrome

1. Click on the three dots at the top right corner
2. Choose Settings

   

3. Click on Reset settings

   

4. Choose Restore settings to their original defaults

   

5. Click Reset settings

   

Remove Windows Defender pop-up from Firefox

1. Click the icon with the three lines on the top right corner
2. Select Help

   

3. Choose More troubleshooting information

   

4. Click on Refresh Firefox...

   

Remove Windows Defender pop-up from Microsoft Edge

1. Click on the three dots
2. Open Settings

   

3. Press on Reset settings

   

4. Click Restore settings to their default values
5. Press Reset

   

Remove Windows Defender pop-up from Safari

1. Open Terminal (press Command + Space to open the Spotlight, type in “Terminal”, and click Enter)

2. Enter these commands one at a time – execute each command by pressing Enter after copying it into the terminal:

rm -Rf ~/Library/Caches/Metadata/Safari;

rm -Rf ~/Library/Caches/com.apple.Safari;

rm -Rf ~/Library/Caches/com.apple.WebKit.PluginProcess;

rm -Rf ~/Library/Preferences/Apple\ -\ Safari\ -\ Safari\ Extensions\ Gallery;

rm -Rf ~/Library/Preferences/com.apple.Safari.LSSharedFileList.plist;

rm -Rf ~/Library/Preferences/com.apple.Safari.RSS.plist;

rm -Rf ~/Library/Preferences/com.apple.Safari.plist;

rm -Rf ~/Library/Preferences/com.apple.WebFoundation.plist;

rm -Rf ~/Library/Preferences/com.apple.WebKit.PluginHost.plist;

rm -Rf ~/Library/Preferences/com.apple.WebKit.PluginProcess.plist;

rm -Rf ~/Library/PubSub/Database;

rm -Rf ~/Library/Safari/*;

rm -Rf ~/Library/Safari/Bookmarks.plist;

rm -Rf ~/Library/Saved\ Application\ State/com.apple.Safari.savedState;

How can I protect my PC against viruses?

The Windows Defender security warning scam is not the only virus that can infect your computer. There are lots of even bigger threats on the internet, and you should take every precaution to avoid them.

Here are the basic measures to protect your device against viruses:

• Use an antivirus to help you identify and remove threats – I recommend TotalAV, now 80% OFF
• Don’t click on random links without knowing where they will lead you to
• Don’t download suspicious applications
• Keep your OS and all software updated
• Don’t open suspicious emails or their attachments
• Use an ad blocker to block malicious ads

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Conclusion

While Windows Defender is a legitimate program, the security warning that appears on your browser is not. In fact, this seemingly harmless pop-up can do a lot of damage if you click on it or decide to call the number it displays.

Luckily, there are a few ways to get rid of it without causing any harm to your device. The most effective ones are restoring your browser settings and scanning the computer with the best PC antivirus software.

Afterwards, you should ensure you don’t get infected with malware again. To do this, practice internet hygiene (e.g., avoid suspicious websites) and get a good antimalware tool to prevent such threats in the first place.

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