How do computer viruses spread?
Computer viruses spread by self-replication. Once inside your Mac or PC, they make copies of themselves and spread via infected email attachments, poisoned macros, or malicious links. A virus might email itself out to your contacts, who then unwittingly send it to their contacts, and so on. That causes the virus infection to spread exponentially — especially if your contacts don’t know the difference between a fake virus warning and real malware detection on their device.
Email is one of the most popular malware delivery methods, so email security is critical. Viruses and other malware can also spread through file sharing and software bundles. When you download an app from a disreputable source outside Apple’s App Store or Google Play, it can come packaged with malicious software or bloatware.
Malware also spreads through vulnerabilities in outdated software. When these vulnerabilities are identified, companies release software updates to patch the issue and prevent viruses and other malware infections from spreading. If you forget to update your software regularly, dangerous hackers can exploit the vulnerabilities in old software to gain access to your device and inject malware.
Viruses can spread to other devices via texts, emails, software vulnerabilities, removable media, or malicious internet downloads.
Signs of a computer virus
To see if your computer has a virus or other malware, look for abnormal behavior, suspicious files or downloads, or frequent crashes. These virus signs will help you detect an infection on both Macs and PCs.
Here are some other signs of a virus infection on your computer:
A very slow computer
Excessive pop-ups that appear out of nowhere and are hard to remove
Unfamiliar programs or apps
Different settings that you didn’t change
Corrupted or erased files
A Whirring or other loud sound coming from your computer or hard drive
An incessantly loud computer fan
An overheating computer
Frequent crashes, freezes, or other unusual behavior
Any one of these symptoms might be caused by a virus or a different kind of malware, like spyware or a cryptominer. If you’re experiencing two or three of them at the same time, that’s a strong indication that you’ve got a virus or that your computer has been hacked.
Removing a virus from a PC
Whether you have a virus or another kind of malware on your laptop or desktop computer, the following steps will help you scan for viruses and get rid of the malware immediately.
1. Download and install antivirus software
There are two main types of antivirus software that can detect and remove computer viruses and malware: real-time and on-demand. A real-time malware scanner scans for viruses in the background while you’re using your computer. An on-demand scanner, like Microsoft Defender, has to be turned on every time you want to check for malware.
For full virus and malware protection — especially against new and emerging threats — install real-time malware scanning and removal software like AVG AntiVirus FREE. AVG offers stronger protection than the standard tools you get from PC manufacturers, whether you’re on a laptop or a desktop computer.
2. Run a virus scan
After installing your antivirus software, you need to check your computer for any malware by running a full virus scan. A comprehensive scanner will search your computer for any malicious code hiding in Windows, and it will get rid of it. Open your antivirus app and select Run Smart Scan. If you have AVG AntiVirus, you can easily set it up to scan your laptop for malware automatically.
3. Delete or quarantine infected files
After scanning your PC, your antivirus software will let you know if any malware is found. Follow the steps to remove the virus or put any infected files into quarantine.
AVG AntiVirus FREE easily removes viruses and prevents future malware infections.
4. Restart your computer
After deleting the infected files from quarantine, restart your computer. Your laptop’s malware infection will be gone.
More virus removal options
If the steps above don’t get rid of the infection, you’ll need to scan your computer more thoroughly in case you have a type of malware — like a Trojan to adware — that’s designed to hide deep in your system.
Enter Safe Mode
First, restart your computer in Safe Mode. Safe Mode launches only Windows’s basic startup settings, such as necessary files, programs, and drivers.
To enter Safe Mode on Windows 10 or Windows 11, hold down the Shift key while selecting Power > Restart. After your computer restarts, select Troubleshoot > Advanced options > Startup Settings. Then, click Restart again. After your laptop or desktop restarts, select 4 (or F4) to enter Safe Mode.
Delete temporary files
Next, erase your temporary files to remove any malicious apps or programs you may have recently downloaded that might have caused your malware infection.
Here’s how to delete temporary files in Windows 10 or Windows 11 while in Safe Mode.
Start typing Disk Cleanup into the search field on the Windows taskbar and select it when it comes up. Then select the drive you want to remove temporary files on. Scroll through the list of files to delete and check the box next to Temporary files. Then click OK.
Removing temporary files will get rid of any malware that recently entered your system — and it can help you speed up your computer, too.
Schedule a boot-time scan
If you can’t get rid of the virus after deleting temporary files, then the malware could be programmed to start when your computer boots up. In that case, you need to run a boot-time virus scan.
A boot-time scan is an advanced antivirus feature designed to root out system-level malware before the operating system and other programs boot up.
Here’s how to run a boot-time scan to check for a computer virus: Open your antivirus app. In the scans tab or in settings, you’ll see an option for a boot-time scan. You should also see options about what to do with any infected files found during the scan — fix them, quarantine them, or delete them. Choose your preferred setting.
After you’ve set up your boot-time scan, the next time you restart your PC, your antivirus will automatically scan your laptop or desktop for any threats. Note that boot-time scans can take a while, so your next restart will likely take longer than normal.
Removing a virus from a Mac
If your Mac has malware, you need to get rid of it fast before the infection spreads. These steps will help you remove malware on a Macbook, iMac, Mac mini, or any other type of Apple computer running the macOS (formerly known as OS X) operating system.
Here’s how to get rid of malware on your Mac laptop or desktop:
1. Install the latest macOS update
Updated software often includes patches that plug security vulnerabilities in previous versions. The latest version of macOS will have the most up-to-date anti-malware protections.
To update macOS, click the Apple icon in the top left of your screen and select About This Mac. Then click More info > Software Update. If an updated version of macOS is available, follow the steps to install it. After installation is complete, restart your computer and your malware problem could be fixed.
2. Use a specialized Mac antivirus tool
The best way to make sure all malware is found and removed is to use antivirus software to scan your Macbook for viruses and malware. An anti-malware app will detect and repair malware infections on macOS, OS X, and other versions of Apple’s operating system.
Here’s how to remove Mac malware with a specialized Mac virus scanner. To begin, download AVG AntiVirus FREE for Mac.
After the download is complete, click the file to begin installation and follow the on-screen instructions. Then, open the app and click Run Smart Scan.
If malicious software, apps, or hidden files are found, follow the on-screen instructions to get rid of the malware on your Mac.
And that’s it. Your Mac malware problem is fixed, and AVG AntiVirus FREE’s non-stop protection against new and emerging threats will keep your computer protected against viruses and malware in the future.
3. Uninstall suspicious apps
If your malware problem persists after you have the latest OS installed and you’re using dedicated antivirus software on your Mac laptop or desktop, it’s time to look more closely at certain apps and programs.
If the virus infection started around the time you downloaded new software, that new software may be responsible for the virus or malware infection. Although the Apple App Store vets apps, malware can sneak through. And if you downloaded anything directly from a developer’s website, it could also contain malware.
Here’s how to get rid of suspicious apps on your Mac to root out a malware infection.
Open Go > Applications and find any suspicious apps (apps with strange names or programs you don’t remember downloading yourself). Right-click on the suspicious app and choose Move to Bin (Move to Trash).
Finally, right-click on your Bin (Trash) and select Empty Bin to make sure the suspicious file is completely removed from your computer.
4. Remove harmful browser extensions
Browser extensions are a common malware vector. If your web browser’s settings have changed and you’re seeing a different homepage, new toolbars, or tons of ads, you may have a browser hijacker or adware infection. Removing these unwanted browser extensions can help get rid of a malware infection and clear viruses from your computer.
Remove browser extensions from Safari
To get rid of malware in Safari browser extensions, open the Safari menu and choose Settings.
Choose Extensions in the top navigation and look for any browser extensions that you don’t remember installing. Select the extensions you don’t need or don’t recognize — these may be malicious — and click Uninstall.
Then, check out our guide to managing your Safari pop-up settings to minimize the risk of inadvertently getting malware from a risky ad or pop-up.
Remove browser extensions from Google Chrome
If you use Google Chrome on your Mac, here’s how to remove browser extensions in Chrome in case they’re concealing malware.
Open Chrome and click the three vertical dots in the upper right of the browser window. Select More Tools > Extensions.
Choose any extensions that may contain malware or that you don’t need and click Remove.
To avoid malicious browser extensions altogether, use a browser with built-in security and privacy that will block malicious extensions automatically, so you won’t need to worry about clearing viruses hiding in extensions anymore.
To learn more about the Mac threatscape, check out our in-depth Mac security guide.
How to prevent viruses and malware in the future
Malware prevention is always easier than malware removal. Here are some quick and easy things you can do to avoid downloading malware on your laptop:
Install the latest software updates.
Software updates include critical security patches. Update your software regularly to stay protected against the latest virus and malware strains.
Get an antivirus program.
Using an antivirus app will protect you against malware and viruses before they infect your computer. The best antivirus software also includes protection against malicious websites, phishing scams, unsafe downloads, and more.
Back up your data regularly.
Many malware strains, especially ransomware, can compromise your data. If you have a backup of all your data, you’ll be able to factory reset your computer without losing anything. Learn more with our complete guide to Mac ransomware.
Be wary of pop-ups.
Avoid clicking on pop-up messages, especially those that claim to have detected a problem with your computer. Pop-ups designed to scare you into downloading unsafe security apps are just malware in disguise.
Watch out for strange emails.
Practice safe email practices, and don’t open emails from unknown or untrusted addresses. If you do happen to open one, don’t click any links and don’t open any attachments.
Use strong antivirus software.
A strong antivirus is your best defense in the fight against online threats. AVG AntiVirus FREE features powerful built-in technology to block dangerous downloads and malicious websites. And with around-the-clock software monitoring, you’ll stay protected against any suspicious activity.
How to prevent Mac malware
Mac malware is on the rise, but some Mac users are still a bit careless about their online security. Here are some tips to avoid viruses and malware on Mac computers.
Keep all your software and apps updated.
Make sure that your Mac is running the latest operating system and that you’ve installed any updates directly from Apple. Opt for auto-updates in the App Store for all apps and OS updates.
Look out for fake Mac antivirus apps.
Some Mac malware poses as an antivirus app — such as MacDefender, MacProtector, and MacSecurity. But, it’s likely just scareware offering to solve a nonexistent problem on your laptop.
If you click, you’re probably downloading malware instead. If you download something malicious from a website, quit your browser, go to your Downloads folder, move new items to the Trash, then empty the Trash. And don’t visit the website again because it’s probably been hacked.
Quit the infected app.
If you think malware has already been installed on your Mac — especially if you’re seeing pop-up messages asking for your Apple ID or credit card details — quit the app that you think might be infected.
Open your Activity Monitor and find the app in question — or search for the malware from the list of names above. When you’ve identified the malware, select it, then click the Stop button. Finally, go into your Applications folder, drag the unwanted software into the Trash, and empty the Trash.
Use specialized Mac antivirus software.
Give your Mac strong malware protection. AVG AntiVirus for Mac is a free and comprehensive cybersecurity tool with real-time protection against malware and other security risks. And it’s updated automatically to safeguard your Mac against the latest online threats.
Can't I just use Windows Defender?
PC users may be wondering if they can simply use Windows Defender — Microsoft’s built-in antivirus program — to stop malware. Although it’s improved in recent years, Windows Defender doesn’t offer as much protection as dedicated antivirus programs.
Windows Defender — now called Microsoft Defender — has had good malware prevention scores in independent tests, but it can struggle to detect new and emerging threats. In a 2021 test from AV-Comparatives, Windows Defender’s virus detection rate was much lower than most third-party security solutions.
Defender also lacks adequate protection against phishing attacks, Wi-Fi threats, and unsafe websites (unless you use Microsoft Edge). Plus, Windows’s own updates have a history of introducing bugs that hamstring Defender’s protection abilities.
Without dedicated antivirus software on your machine, Windows Defender will provide some level of protection for your PC. But to defend against the wide array of threats — and emerging threats like zero-day attacks — we recommend AVG AntiVirus FREE, a comprehensive security suite that scores higher in AV Comparatives tests and provides more advanced features.
Are my other devices safe?
Any device connected to an infected computer is vulnerable to malicious software. While a traditional computer virus is unlikely to spread to mobile devices, Android phones and tablets are susceptible to mobile spyware, Android ransomware, and other phone hacking tricks.
iOS devices are a bit more resistant to malware than Androids. That mainly has to do with Apple’s defenses, such as app sandboxing and security updates on all devices — but your iPhone isn’t immune to threats. Phishing scams, unsafe Wi-Fi networks, and identity theft can all affect iOS users. For more information, check out our guide to the best security apps for your iPhone.
If your phone has been acting strangely and you think there’s an infection, learn how to remove a virus and malware from your phone. Or, get an app that will do it for you:
Get rid of viruses and malware the easy way
If you want to learn how to remove a virus from a PC or get rid of malware on Mac, the easiest way is to use a robust antivirus program from a reputable developer. AVG AntiVirus FREE works around the clock to give you comprehensive threat protection.
Remove all traces of malicious software from your laptop or desktop computer and stay safe against future infections and emerging threats. Download AVG today and join the world’s largest threat detection network.