How to check if my computer has a virus

Windows Security is a powerful scanning tool that finds and removes malware from your PC. Here's how to use it in Windows 10 to scan your PC.

Important: Before you use Windows Defender Offline, make sure to save any open files and close apps and programs.

Open your Windows Security settings.
Select Virus & threat protection > Scan options.
Select Windows Defender Offline scan, and then select Scan now.

The Windows Defender Offline scan takes about 15 minutes to run, and then your PC will restart.

View the results of your scan

Open your Windows Security settings.
Select Virus & threat protection > Protection history.

The Windows Defender Offline scan will automatically detect and remove or quarantine malware.

If your computer is acting strangely, you may be wondering, “Do I have a virus?” There are several telltale signs your device may have a virus, including slow performance and certain types of pop-ups. We’re sharing those and other signs, plus steps you can take to get rid of the virus.

Computer viruses are about as diverse as computer users. There can be thousands of new viruses and malware attacks each year, and they can affect devices and operating systems in many different ways. However, virus warning signs tend to be similar across the board. Here’s how to help know if your computer has a virus.

9 signs of a computer virus

1. Slow-down of your computer’s performance

Are your files and apps taking a long time to load? Is your computer taking a longer time to start and runs slowly once it does? If so, it’s possible a virus is infiltrating your operating system.

2. Endless pop-ups and spam

Frequent and odd pop-up windows are red flags. Pop-ups might prompt you to visit other websites to download antivirus or other software programs, which instead may install malware. Malicious pop-ups and spam may also secretly install spyware that could hijack your browser or steal your passwords and other personal information without your knowledge.

3. You’re locked out of your computer

If you’re unable to gain access to settings and files on your own computer — or you can’t log on or off — malware has likely taken over.

4. Changes to your homepage

Is your homepage randomly switching to another website? Are you unable to reset it? If so, you likely have a virus. Viruses can implement changes to your homepage and create error messages, browser errors, and shortcut files.

5. Unknown programs starting on your computer

Computer viruses can create widespread problems. Adding icons and toolbars that you didn’t set up is just the tip of the iceberg. If unknown programs load when you turn on your computer or another connected device, turn it off. You’ve been infiltrated.

6. Mass emails sent from your email account

Have you ever received an odd email from a friend that made you suspect someone hacked into their email account? If your email’s outbox contains messages you didn’t send, your social media accounts have posts you didn’t make, or you can’t log into your email or social media accounts, your computer has likely been compromised.

7. Your security software has been disabled

If your antivirus program or security software has stopped working and you didn’t disable it, it’s possible that malware has taken over.

8. Your battery drains quickly

Here’s another sign that a virus may have infected your computer and is multiplying: a drained battery. As the virus continues to multiply, it uses resources from your computer and creates more activity on your computer. As a result, your battery life is diminished.

9. Frequent crashes

Does your computer randomly crash on you? Does your screen freeze and become the infamous ‘blue screen of death’? This could be a sign that your device has been infected with a virus.

How a computer gets a virus

A computer virus infiltrates a computer and its programs similar to the way the flu infects your body’s immune system and multiplies. Viruses can be installed on your computer without your knowledge or consent, and can insert new, malicious code that can monitor and manipulate your online activity.

Some malware may not seem serious, but it can lead to big problems. For example, criminals could use a virus to gain access to your personal information, allowing them to commit identity theft and other types of fraud.

How to check for and remove viruses

You can attempt to remove a computer virus yourself, but unless you’re an expert, it can be complicated.

A simpler approach is to install antivirus software from a reliable company. You can let the professionals do it for you to ensure you’re not leaving your computer vulnerable. An antivirus program, also known as security software, may also scan your external hard drive when it’s plugged in, but keep in mind not every program checks the hard disk.

Here’s a basic plan to check for and remove computer viruses.

Step 1: Run a security scan

Run a security scan using security software to check for viruses and malware.

Step 2: Remove existing viruses

You can then remove existing viruses and malware using a service like Norton Power Eraser. It will perform a scan and give you onscreen instructions. If needed, you can call Norton for technical assistance. After following the instructions, restart your computer.

Step 3: Update security system

Make sure your computer’s software is updated with the latest protections. For instance, when you’re notified of a Windows update or web browser update, it’s a good idea to install the latest version right away.

Set your security software, web browser and operating system (such as Windows or Mac OS) to update automatically. This helps keep your operating system up-to-date and ready to detect and handle the latest viruses.

How to help protect your computer against viruses

Once you’ve updated your software and secured your devices with software, there are simple and practical steps you can take to protect yourself, including these.

Reset the passwords to all of your accounts

Make sure your passwords are strong by including upper and lowercase letters along with numbers and symbols. Each account should also have its own unique password. A password manager can help you create, track, and manage multiple passwords. You might also want to consider a passphrase, a string of words that might be easy to remember but hard for someone to guess.

Use a pop-up blocker

A pop-up blocker can help you block unwanted ads. Never click on random pop-ups if they do appear on your screen.

Only download from sites you trust

Don’t download content from a website unless you know you can trust it. (You can check the safety of a website using Safe Web.) Use caution when downloading free software onto your computer because it may be malware in disguise. It’s a good idea to make sure the software is from a reputable provider and to check reviews.

The bottom line? Don’t make it easy for cyberthieves to infiltrate your computer. Instead, keep an eye on your computer activity, be cautious about your own activity, and ensure you’ve updated your antivirus software and operating system with the latest protections.

It’s like wearing a mask or washing your hands during cold and flu season. Viruses may float around, but you’ll be helping to protect your system so they have a lesser chance of infecting your devices.

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Editorial note: Our articles provide educational information for you. NortonLifeLock offerings may not cover or protect against every type of crime, fraud, or threat we write about. Our goal is to increase awareness about cyber safety. Please review complete Terms during enrollment or setup. Remember that no one can prevent all identity theft or cybercrime, and that LifeLock does not monitor all transactions at all businesses.

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