How to Clean a Computer of Malware

This wikiHow teaches you how to find and remove malware from your Windows or Mac computer. Typically speaking, an antivirus scan will be enough to remove most major threats to your computer. If you're having trouble with your malware removal, however, the best way to prevent the malware from spreading is by backing up your files and then reinstalling your computer's operating system.

Method 1
Method 1 of 4:

Scanning for Malware on Windows

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    Open Start
    Windows Start
    .     Click the Windows logo in the bottom-left corner of the screen.
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    Open Settings
    Windows Settings
    .     Click the gear-shaped icon in the lower-left side of the Start window.
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    Click
    Windows Update = Windows
    Update & Security.     This icon resembles a circle made of two arrows.
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    Click Windows Defender. It's a tab in the upper-left side of the window.
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    Click Open Windows Defender Security Center. This button is at the top of the window. Clicking it opens the Windows Defender program, which is the Windows built-in antivirus software.
    • Windows Defender is the recommended antivirus software for Windows computers. Using any other software in conjunction with Defender may cause problems such as an inability to shut down.
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    Click ☰. It's in the top-left corner of the Windows Defender window. A pop-out menu will appear.
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    Click Virus & threat protection. You'll see this in the pop-out menu.
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    Click Advanced scan. It's a link just below the Quick scan button.
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    Check the Full scan option. This is at the top of the window.
    • If you're encountering malware issues and this scan doesn't solve them, you can try using the Offline scan option on this page to perform a deeper, file-based scan.
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    Click Scan now. It's in the middle of the page. Windows Defender will begin scanning your computer for infected files.
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    Wait for results. Windows Defender will alert you if it comes across viruses or other instances of Malware, at which point you'll be able to indicate that you want Defender to remove the malware in question.
    • A malware scan can take several hours to complete.
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Method 2
Method 2 of 4:

Scanning for Malware on Mac

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    Download Malwarebytes. Go to https://www.malwarebytes.com/mac-download/ in your browser to prompt Malwarebytes to begin downloading. Macs don't come with a built-in antivirus program, so Malwarebytes is your best bet.[1]
    • Although Malwarebytes offers a paid premium version with real-time protection, you can use the free version to scan your computer and remove viruses or malware at any time.
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    Open Finder
    Mac Finder
    .     If your Mac's Finder program isn't already open, click the blue, face-like app icon in the Dock to open it.
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    Find and double-click the Malwarebytes DMG file. You'll most likely find it in the Downloads folder that's on the left side of the Finder window. The DMG file will either open or result in an error message.
  4. 4
    Verify the software installation. You'll need to do this if you receive an error message when attempting to open Malwarebytes.
    • If Malwarebytes is recognized as a signed developer on your Mac, you won't have this step.
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    Double-click the "Malwarebytes 3" file. This file resembles a white box with a dark-blue Malwarebytes logo on it. Doing so will open the setup window.
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    Set up Malware bytes. Navigate through the setup by doing the following:
    • Click Continue
    • Click Agree
    • Click Install
    • Enter your username and password.
    • Click Install Software
    • Click Close when prompted.
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    Open Malwarebytes. Click Spotlight
    Mac Spotlight
    , type malwarebytes into Spotlight, and click the Malwarebytes result at the top of the search results.
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    Click the Dashboard tab. It's in the upper-left corner of the Malwarebytes window.
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    Click Scan Now. This button is at the bottom of the window. Doing so will prompt Malwarebytes to begin scanning your Mac for malicious software.
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    Click the Scan tab. You'll find it on the left side of the window.
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    Click Confirm when prompted. It's at the bottom of the Malwarebytes window. If any malicious programs are found, Malwarebytes will immediately quarantine those files on your Mac so they will no longer harm your computer.
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Method 3
Method 3 of 4:

Reinstalling Windows

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    Back up any files that you want to save. Since you'll be erasing your computer's hard drive and then reinstalling Windows onto it, make sure that any files which you want to save are backed up onto an external hard drive (or cloud storage).
    • Keep in mind that malware often attaches itself to files or programs. If you suspect that a program that you downloaded is the reason for an infection, do not back that file up to your external hard drive.
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    Open Start
    Windows Start
    .     Click the Windows logo in the bottom-left corner of the screen.
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    Open Settings
    Windows Settings
    .     Click the gear-shaped icon in the lower-left side of the window.
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    Click
    Windows Update = Windows
    Update & Security.     It's an icon that resembles a circle made up of arrows.
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    Click the Recovery tab. You'll find this tab on the left side of the window.
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    Click Get started. It's a button below the "Reset this PC" heading at the top of the page. A pop-up window will appear.
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    Click Remove everything. This option is at the bottom of the pop-up window.
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    Click Remove files and clean the drive. It's at the bottom of the pop-up window.
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    Click Reset when prompted. Doing so will allow your computer to begin erasing and reinstalling Windows.
    • This process can take several hours, so make sure that your computer is plugged into a reliable power source.
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    Set up your computer. This will generally consist of selecting a region, a language, a timezone, and your Microsoft email address.
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Method 4
Method 4 of 4:

Reinstalling macOS

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    Back up any files that you want to save. Since you'll be erasing your computer's hard drive and then reinstalling macOS onto it, make sure that any files which you want to save are backed up onto an external hard drive (or cloud storage).
    • Keep in mind that malware often attaches itself to files or programs. If you suspect that a program that you downloaded is the reason for an infection, do not back that file up to your external hard drive.
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    Begin restarting your Mac. Click the Apple menu
    Mac Apple
    , click Restart... in the resulting drop-down menu, and click Restart when prompted.
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    Hold down ⌥ Option+⌘ Command+R. Do so immediately after clicking Restart, and don't stop holding down these keys until the Apple logo appears.
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    Wait for the Apple logo to appear. This may take between 10 and 20 seconds.
    • For some computers, you'll see a spinning globe appear instead.
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    Release ⌥ Option+⌘ Command+R. Once you see the Apple logo appear, you can release the keys. The setup window will appear after a few seconds.
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    Click Disk Utility. It's in the setup window.
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    Click Continue. You'll see this button in the bottom-right corner of the setup window.
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    Select your Mac's hard drive. On the left side of the window, click the Mac's hard drive.
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    Click Erase. This tab is at the top of the Disk Utility window. A pop-up window will appear.
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    Select a format. Click the "Format" drop-down box, then click Mac OS Extended (Journaled) in the resulting drop-down menu.[2]
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    Click Erase. It's at the bottom of the window. This will prompt your hard drive to begin erasing everything on it, including any leftover malware.
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    Wait for your hard drive to finish erasing. This can take several minutes to an hour or more, so just make sure that your Mac is connected to a reliable power source. Once the hard drive finishes erasing, you'll be taken back to the setup page.
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    Click Reinstall macOS. It's in the middle of the setup window.
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    Click Continue. This is in the bottom-right corner of the window.
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    Follow the setup prompts. You'll most likely be asked to enter your Apple ID and select a disk (e.g., your Mac's hard drive) for installation.
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    Click Install when prompted. Doing so will allow your Mac to begin installing a fresh copy of the most recent version of macOS.
    • You'll have to set up your Mac's preferences once the installation is complete.
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Expert Q&A
Did you know you can get expert answers for this article? Unlock expert answers by supporting wikiHow

  • Question
    Is Malwarebytes safe?
    Jeremy Mercer
    Jeremy Mercer
    Computer Repair Technician
    Jeremy Mercer is the Manager and Head Technician at MacPro-LA in Los Angeles, CA. He has over ten years of experience working in electronics repair, as well as retail stores that specialize in both Mac and PC.
    Jeremy Mercer
    Jeremy Mercer
    Computer Repair Technician
    Expert Answer

    Support wikiHow by unlocking this expert answer.

    Yes, Malwarebytes is a very reputable and safe program. You're not putting your computer at risk by downloading or using it. Just make sure you get it from the source, and not from some random website that has nothing to do with the company that makes it.
  • Question
    Do antivirus programs clear out malware?
    Jeremy Mercer
    Jeremy Mercer
    Computer Repair Technician
    Jeremy Mercer is the Manager and Head Technician at MacPro-LA in Los Angeles, CA. He has over ten years of experience working in electronics repair, as well as retail stores that specialize in both Mac and PC.
    Jeremy Mercer
    Jeremy Mercer
    Computer Repair Technician
    Expert Answer

    Support wikiHow by unlocking this expert answer.

    Most of the decent antivirus programs have some kind of malware scanner built in. You can use that to remove malware if you'd like; you won't need to download another program to do it.
  • Question
    Does CC Cleaner remove malware?
    Jeremy Mercer
    Jeremy Mercer
    Computer Repair Technician
    Jeremy Mercer is the Manager and Head Technician at MacPro-LA in Los Angeles, CA. He has over ten years of experience working in electronics repair, as well as retail stores that specialize in both Mac and PC.
    Jeremy Mercer
    Jeremy Mercer
    Computer Repair Technician
    Expert Answer

    Support wikiHow by unlocking this expert answer.

    No, although CC Cleaner is a very helpful program. CC Cleaner goes through and removes all of the junk files and clears your cache. That will help your computer run a little faster and clear out the stuff you don't use. It won't remove any viruses or malware, though.
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References

  1. ↑ Jeremy Mercer. Computer Repair Technician. Expert Interview. 26 July 2019.
  2. ↑ https://support.apple.com/en-us/HT204904

About This Article

Jeremy Mercer
Co-authored by:
Jeremy Mercer
Computer Repair Technician
This article was co-authored by Jeremy Mercer and by wikiHow staff writer, Jack Lloyd. Jeremy Mercer is the Manager and Head Technician at MacPro-LA in Los Angeles, CA. He has over ten years of experience working in electronics repair, as well as retail stores that specialize in both Mac and PC. This article has been viewed 64,317 times.
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Co-authors: 11
Updated: January 31, 2023
Views: 64,317
Categories: System Maintenance and Repair
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