How to Detect and Remove Malware From Your Computer

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What to do if you notice unusual activity on your Mac or Windows computer
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Malware, short for “malicious software,” has the ability to infect your computer to the point where it collects your personal data, gains access to programs or systems on your network, and prevents your computer from running efficiently. There are several signs that can indicate whether your computer has been infected by malware, and certain steps you can take to detect and remove all malware from your computer. This wikiHow teaches you how to detect malware on your computer, with tips from Cybersecurity Expert Michael Thompson-Brown.

Detecting Malware

If your computer is running slowly, freezing, or crashing, this may be a sign of malware. You can run a virus scan using the built-in Windows Security application or a third-party application such as Malwarebytes. Most Mac users don't need malware protection as Mac guards against downloading applications from unidentified developers.

Section 1 of 5:

Checking Computer Behavior

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  1. If your web browser is changing your home page or redirecting you to unexpected pages while browsing the internet, your computer may be infected with malware.
  2. If you see new toolbar items, browser extensions, or icons you don't remember installing, your computer may be infected by malware.
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  3. Most malware will run tasks in the background that consume a higher percentage of your computer’s resources. If your computer is running slow, even without any other programs running, your computer may be infected with malware.
  4. You can use the Task Manager on Windows or Activity Monitor on Mac to see if there are any unfamiliar apps or processes running in the background. Keep in mind that some forms of malware may try to disguise themselves as legitimate programs.
    • To open the Task Manager on Windows, press Ctrl + Alt + Del and then click Task Manager. See what programs are running under the "Processes" tab.
    • To open Activity Monitor on Mac, click the Spotlight search icon in the menu bar at the top. Enter "Activity Monitor" in the search bar. Then click Activity Monitor . Check the programs that are running under "Process Name."
    EXPERT TIP

    Michael Thompson-Brown

    Cybersecurity Expert
    Michael Thompson-Brown is a Cybersecurity Expert based in Portland, Maine. He is the owner and founder of PCRescue!, a company that provides cybersecurity and data management solutions to small businesses and individuals. Michael has over 25 years of experience in the IT industry and is a certified ethical hacker. He is passionate about helping clients protect their data and systems from malicious attacks and helping them optimize their online presence and reach. He received a Master’s degree in Cybersecurity and Information Assurance from Western Governors University, and a Bachelor’s degree in Business Administration from the University of Phoenix.
    Michael Thompson-Brown
    Cybersecurity Expert

    Unusual behavior is one of the best indicators of malware. I always suggest people open the Task Manager and see what is running. Although it can be hard to identify what programs are good and bad.

  5. Some malware has the ability to temporarily disable the antivirus software and firewalls on your computer without your consent. Check if your antivirus software and firewall software are running .
    • To check your firewall settings on Windows, click the WIndows Start menu and type "Windows Security". Open Windows Security and click Firewall & network protection . Follow the prompts if there are any actions that need to be taken.
    • To check your firewall settings on a Mac, click the Apple icon and click System Settings (or System Preferences ). Click Network in the menu bar to the left (or Security & Privacy on older versions of macOS). Then click the Firewall tab. Ensure your firewall is turned on.
  6. Some malware will corrupt or delete certain files that are required for your computer to run efficiently. If your operating system or certain applications freeze, run slowly, or crash randomly and unexpectedly, you may have malware on your machine.
  7. In some cases, malware infections will prevent you from being able to use your mouse, printer, and keyboard, and could even disable certain features. If you are unable to use normal functions on your computer, your computer may be infected with malware.
  8. Sometimes malware will corrupt your computer and cause it to display strange or unusual error messages when you try to use or access certain programs. Frequent error messages can indicate that your computer is infected with malware.
  9. If you notice strange email messages in your outbox that you did not compose, or posts and direct messages in your social media accounts that you did not personally send, then your system may have been infected with malware. [1]
  10. If your computer has been infected by malware, you may receive a lot of pop-ups and advertisements. Do not download any software advertised through a pop-up, even if it's advertising antivirus or antimalware software. Always download software from trusted websites.
  11. Malware can be sneaky. Sometimes it disguises itself as legitimate software. Not all computer problems are the result of malware infections. In some cases, you may need the help of a computer repair or computer security expert in order to identify and remove malware.
    EXPERT TIP

    Michael Thompson-Brown

    Cybersecurity Expert
    Michael Thompson-Brown is a Cybersecurity Expert based in Portland, Maine. He is the owner and founder of PCRescue!, a company that provides cybersecurity and data management solutions to small businesses and individuals. Michael has over 25 years of experience in the IT industry and is a certified ethical hacker. He is passionate about helping clients protect their data and systems from malicious attacks and helping them optimize their online presence and reach. He received a Master’s degree in Cybersecurity and Information Assurance from Western Governors University, and a Bachelor’s degree in Business Administration from the University of Phoenix.
    Michael Thompson-Brown
    Cybersecurity Expert

    Malware can be hard to identify on a normal system. Most problems and odd behavior are not the result of an infection. If you suspect your computer has a malware infection, the best thing to do is to take it to a professional and have it checked out.

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Section 2 of 5:

Using Windows Security

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  1. Windows Security comes pre-installed on all versions of Windows 10 and 11. It includes virus protection, which you can use to scan for viruses and malware. Enter "Windows Security" in the Windows search bar and then click Windows Security .
  2. It's the first option in Windows Security.
  3. This will begin scanning your computer for viruses and malware. If any threats are detected, follow the prompts to remove or quarantine the threats.
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Section 3 of 5:

Using Malwarebytes

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  1. Malwarebytes is a reputable antivirus/antimalware that is available for Windows and macOS. You can use the free version of Malwarebytes to scan for viruses on your computer. There is also a paid subscription that has additional features, such as automatic protection. Use the following steps to download and install Malwarebytes:
  2. You can open Malwarebytes in the Windows Start menu or the Applications folder on Mac.
  3. This will begin scanning your computer for viruses and malware. When the scan is complete, follow the prompts to remove or quarantine any threats detected.
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Section 4 of 5:

Malware on Macs

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  1. MacOS is a Unix-based operating system that isn't as susceptible to viruses or malware as Windows. However, that does not mean that macOS is immune to viruses and malware. MacOS prevents malware by blocking you from downloading software from unknown sources rather than scanning your system for malware that has already been installed. Do not allow macOS to install apps that it has blocked. Use the following steps to select what apps you can download on your system: [2]
    • Click the Apple icon in the menu bar.
    • Click System Settings .
    • Click Privacy & Security .
    • Scroll down to the "Security" header and select one of the following options using the drop-down menu:
      • Select App Store to only allow apps from the App Store (most secure).
      • Select App Store and identified developers to allow apps from the App Store and authorized developers (less secure).
    • Click Allow in the Privacy & Security menu to allow an app from an unidentified developer to be installed (not recommended). You have to try to install the program before this option will appear in the menu.
  2. If your Mac is running incredibly slow, you get a lot of website redirects, you notice apps you didn't install on your Mac, or you are unable to access your files, you may have malware. In that case, you can download Malwarebytes and run an antivirus scan.
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Section 5 of 5:

Preventing Malware

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  1. When downloading software or applications, make sure you are using an official website that is reputable. Do not use unfamiliar websites to download programs, applications, music, or videos.
  2. Avoid downloading files or programs through peer-to-peer applications or from Torrent files. These may contain viruses and malware. [3]
  3. Viruses and malware can be sent as email attachments. Avoid downloading email attachments from senders you don't recognize.
  4. Phishing is when someone sends you a malicious link pretending to be from an official source. These links may trick you into entering personal login information or downloading malware. If you receive an email or text message from someone claiming to be from an official organization telling you there is a problem with your account and asking you to click a link, do not click it. Contact the organization directly or use their official website.
  5. If you are using third-party antivirus software, make sure you check for updates before running a virus scan. Otherwise, it may not be able to detect the latest threats.
  6. If someone hands you a USB drive, use your antivirus program to scan the drive before downloading anything off the drive. Do not use USB drives that you find or are given to you by a stranger.
  7. Updating your operating system can be annoying. However, system updates often contain vital security patches. If you suspect you have malware on your computer, make sure your operating system is up-to-date. Use one of the following steps to update your system:
    • WIndows: You can update Windows by clicking the Windows Start menu and typing "Update." Click Check for updates . Click Install all .
    • Mac: Click the Spotlight search icon in the menu bar. Type "Software update" in the search bar. Click Software Update Click Update or Upgrade if an update is available.
  8. The programs you use may also contain vulnerabilities that can be exploited by hackers. Be sure to keep the programs you use updated to patch out any security threats.
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Community Q&A

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  • Question
    Can malware cause pornographic videos and images to appear?
    Living Concrete
    Top Answerer
    Yes, malware can cause this to happen.
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  • Question
    Will malware cause your computer to have a very short battery life and also stop and start charging when on the charger?
    Community Answer
    It wouldn't be directly affecting the battery, but a virus or malware could be increasing the amount of processing that the phone's processor is having to do by adding additional tasks running in the background on the phone. And that would reduce your battery life by drawing more power from it.
    Thanks! We're glad this was helpful.
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  • Question
    Any tips to avoid malware on iOS/Android? Also, are slow internet loading times symptoms or just WiFi issues?
    Jude Young
    Community Answer
    Try using an Android malware detecting/removal tool such as Kaspersky internet security for Android, and slow internet loading times can be symptoms of malware like Trojans and/or they can be WiFi issues.
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      Tips

      • Mac computers are less susceptible to malware than Windows computers, but may still benefit from antivirus applications. For Mac computers, experts in the computer security industry recommend using antivirus programs such as iAntivirus from Norton, Avira Free Mac Security, Comodo Antivirus for Mac, and Avast Free Antivirus for Mac.
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      Warnings

      • Before downloading any antivirus or malware scanning software, verify that the website you’re downloading software from is reputable and legitimate. Some websites may offer malware disguised as antivirus software that will impair and infect your machine.
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      References

      1. ↑ https://www.digitaltrends.com/computing/computer-virus-symptoms/
      2. ↑ https://support.apple.com/en-ie/guide/mac-help/mh40596/mac
      3. ↑ https://consumer.ftc.gov/articles/malware-how-protect-against-detect-and-remove-it

      About This Article

      Article Summary X

      1. Check if you are gettings lots of pop-ups and ads.
      2. Check if you see any new toolbar items, browser extensions, and software icons you didn't install.
      3. Check if your home page changes or you are redirected to other web pages unexpectedly.
      4. Check if your computer is running slower than usual.
      5. See if your antivirus software and/or firewall software has been disabled.
      6. Note if your computer's normal functions aren't functioning anymore.
      7. Note if your computer crashes a lot or gets a lot of error message.
      8. Scan for malware using Windows Security or a trusted third-party malware scanning application.

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