Fake virus warning pop-up with a phone number? What to do

27 October 2026

You’re browsing normally when the screen fills with a red warning: your computer is infected, your files are at risk, call Microsoft support on this number now. There may be a loud alarm or a voice message, and the page won’t close. It looks frightening, which is exactly the point. This is a tech support scam, and in most cases nothing has actually happened to your computer yet. Here is how to get rid of the pop-up safely, and what to do if you’ve already called the number.

How to spot a fake warning

• It gives you a phone number to call. Microsoft, Apple and real antivirus programs don’t put phone numbers in virus warnings.
• It appears in your web browser, often in full screen, rather than in your antivirus program.
• It uses pressure: countdowns, alarms, claims your bank details are being stolen, or warnings not to switch off.
• It uses logos from Microsoft, Windows Defender, Apple or McAfee to look official. Logos are easy to copy.

Closing the pop-up safely

Don’t call the number, and don’t click anything on the page, including buttons that say “close” or “cancel”.

1. Try pressing Esc to leave full-screen mode, then close the browser tab or window.
2. On Windows, if the browser won’t close, press Ctrl + Shift + Esc to open Task Manager, select your browser (Chrome, Edge or Firefox) and click End task.
3. On a Mac, press Cmd + Option + Esc, select the browser and click Force Quit.
4. When you open the browser again, don’t restore the previous session or tabs if it offers, or the scam page will come straight back.

If the warnings keep appearing in the corner of the screen even when you aren’t on that site, you may have accidentally allowed the site to send notifications. Check your browser’s settings for site notifications and remove any you don’t recognise.

If you called the number

The scammers usually try three things: get you to install a remote access program so they can control your computer, get you to pay for “support”, often by bank transfer or gift cards, and get your passwords or banking details. What you should do depends on how far it went.

You talked to them but didn’t install anything or pay

Hang up. You haven’t lost anything. Be wary of follow-up calls: scammers often call back claiming to offer a refund or to be from your bank.

You let them connect to your computer

• Disconnect from the internet and switch the computer off.
• From a different device, change the passwords for your email first, then online banking and any other important accounts. Your email matters most, because it can be used to reset everything else.
• Don’t use the computer for banking or email until it has been checked. Scammers often leave remote access software behind so they can get back in later.

You paid them or shared bank details

• Call your bank immediately. Use the number on the back of your card, or call 159, which connects you to many UK banks’ fraud teams. The sooner you call, the better the chance of stopping a payment.
• Report it to Action Fraud, the UK’s national reporting centre for fraud and cybercrime (in Scotland, report it to Police Scotland on 101).
• If you bought gift cards, contact the company that issued them straight away with the card numbers and receipt.

Why the computer still needs checking

Even after you change your passwords, the computer may still hold remote access software such as AnyDesk, TeamViewer or a lesser-known tool, sometimes set to start automatically. Scammers have also been known to install other unwanted programs, create new user accounts or change security settings. Removing the program from the Windows apps list isn’t always enough. A proper check looks for anything that lets someone connect, anything that starts at boot, and any changes to accounts and security settings.

Avoiding it next time

• Remember that no real company will ever ask you to call them because of a pop-up, or call you out of the blue about a virus.
• Keep your browser and operating system up to date.
• Be careful with ads at the top of search results that look like official support pages.
• Forward scam emails to report@phishing.gov.uk and scam texts to 7726.

Get your computer checked in London

If someone connected to your computer, or you’re not sure what they did, switch it off and bring it to us. We remove any remote access software and anything else the scammers left behind. See scam call and pop-up help for details, or malware and adware removal if you’re seeing ads and redirects. If you’re worried about losing files, read about deleted file recovery.

Walk in to 80 Willow Walk, Unit 1, London SE1 5SY, Monday to Saturday, 9am to 6pm, or call 020 7394 2521.

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