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A pop-up says your computer is infected. Is it real?

By Losa · Last reviewed September 24, 2026 · 3 min read

If a message filled your screen saying your computer is infected, locked, or "compromised", and it gave you a phone number to call, take a breath. It is almost certainly a scam, and closing it is usually all you need to do.

How to tell it's fake

Scam pop-ups are designed to look official and to rush you. They usually have several of these signs:

• A phone number to "call Microsoft support" or "call Windows Defender". This alone is enough to know it's fake.
• It's inside your web browser. Look closely and you'll often see the browser's tabs or address bar behind it. Real Windows Security alerts appear in the corner of the screen or in the Windows Security app, not on a web page.
• Alarms, a robotic voice, or a countdown timer warning that your files will be deleted.
• Claims your bank account or identity is under attack, and that you need to act "before it's too late".
• The browser goes full-screen and seems impossible to close.

That last one is what makes these so frightening. But the page can't actually do anything to your computer. It's a web page pretending to be something else.

How to close it safely

Don't click anything inside the pop-up, including buttons that say "Close" or "Cancel", because they can be part of the trick. Instead:

1. Try pressing Esc to leave full-screen mode, then close the browser tab or window normally.
2. If that doesn't work on Windows, press Ctrl + Shift + Esc to open Task Manager, select your browser (Chrome, Edge or Firefox), and click End task.
3. On a Mac, press Command + Option + Esc, choose your browser and click Force Quit.
4. When you reopen the browser, if it offers to "restore pages", say no. Otherwise the scam page may load again.

If the pop-ups keep coming back, a website may have been given permission to send you notifications, or a browser extension may be causing them. Our guide to stopping pop-ups and browser hijackers covers how to fix both.

Want to be sure? Run a scan

Closing a scam page doesn't usually leave anything behind. But if you want reassurance, run a scan with the protection already on your computer. On Windows, see how to run a full scan with Windows Security. If you already have antivirus installed, open it from your Start menu or Applications folder, never from a link in a pop-up.

If you already called the number

Many people do. These scams are built by professionals to feel convincing. What to do next depends on what happened on the call:

If you let them connect to your computer

• Disconnect from the internet (turn off Wi-Fi or unplug the network cable).
• Uninstall any remote-access software they asked you to install. Common ones include AnyDesk, TeamViewer and similar tools, and they appear in your list of installed programs.
• Run a full scan with your security software.
• From a different device, change the passwords for your email, bank and any accounts you logged in to while they were connected.

If you paid them

• By card: call your card company using the number on the back of your card and ask to dispute the charge.
• By gift card: contact the company that issued the gift card immediately and tell them it was used in a scam. Keep the card and receipt.
• By bank transfer, cryptocurrency or wire: contact your bank or the service you used straight away. The sooner you act, the better the chance of stopping it.

If they said your bank account was being hacked

Newer versions of this scam hand you to a second person pretending to be from your bank, the FTC or the FBI, who tells you to move your money somewhere "safe". No real bank or government agency will ever ask you to move money to protect it. Hang up and call your bank using a number you know is real.

Report it

Reporting helps authorities track and shut these operations down. You can report tech support scams to the FTC at ReportFraud.ftc.gov.