'Windows Defender Security Warning' pop-up: it's fake

A page claiming to be a 'Windows Defender Security Warning' — often saying access to this PC has been blocked for security reasons, with a Microsoft support number to call — is not from Windows Defender. It is a scam web page using Defender's name and colours. Real Defender alerts appear in the Windows Security app and in notifications; they never display a phone number and never block your whole screen through a browser.

Close it the safe way

  1. Don't click the page's own buttons or call the number.
  2. Press Esc to exit full-screen if it's locked there.
  3. Press Ctrl+Shift+Esc, pick your browser in Task Manager, End task.
  4. Reopen the browser and decline any 'restore pages' offer.
  5. Open the real Windows Security app → Virus & threat protection → run a Full scan (or Microsoft Defender Offline scan) for peace of mind.

Why it looks so convincing

The page copies Defender's blue, its shield wording, and phrases like 'threat detected' and 'access blocked'. Underneath, it's an ordinary web page — frequently reached through a poisoned ad or a mistyped address — styled to fill the screen and sometimes paired with a recorded voice warning. None of that styling gives it any access to your PC.

Microsoft's real support never starts this way. Microsoft does not call you, does not put support numbers in error pages, and does not ask for payment to 'unblock' a computer. Any page that does is impersonating them.

If you called or paid

Follow the recovery steps on the tech support scam pop-up page: remove any remote-access tool they installed, dispute the charge with your bank, change key passwords from a clean device, and run the full Defender scan.

Common questions

How can I tell a real Defender alert from this fake one? Real Defender findings show up inside the Windows Security app (Virus & threat protection) and as small system notifications — with buttons like 'See details', never a phone number and never a full-screen browser page. If it's in a browser tab and it wants you to call someone, it's fake.

It says my PC is blocked. Is it? No. The 'block' is the web page itself, usually full-screen with the mouse cursor hidden or a fake dialog. Ending the browser process (Task Manager → End task) removes it completely.

Related

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