How to Check Your Mac for Viruses and Malware

You love your Mac.  


You pamper it with the nicest cases and feed it the latest software, and it reciprocates by working without a single hiccup.  


Until one day when a security scan you didn’t run detects 1,283 issues. Or your browser’s homepage suddenly changes. Or your Mac slows down so much that it’s unusable.  It seems the unthinkable has happened and you’ve caught a computer virus.


Don’t panic. In a few minutes, you’ll know how to check for malware on a Mac and:

Can Macs get viruses?

Yes. Unfortunately, Mac computers are not immune to malware. However, it’s rarely a classic virus that gets into your computer and replicates itself until you have no free space — Macs are well protected against those. Instead, you should look out for other kinds of unwanted, more sophisticated programs.  

Signs your Mac is infected

Remember: always use antivirus software from reputable vendors to check your Mac for malware. A thorough local scan of your computer is the only sure way to tell if you’ve been infected or not.


Don’t trust webpages, notifications, or emails claiming your Mac is infected. It’s mostly by clicking these links that users introduce malware into their computer systems.


Here are several red flags indicating it’s time to give your Mac a virus scan.

  • Your Mac is slower than usual. This could be a sign of someone using your machine for mining cryptocurrency or running DDOS attacks — not something you’d normally partake in.
  • You start seeing annoying security alerts, even though you didn’t run any scans. Scareware could be the culprit here. It’s a kind of malware capable of pressuring you into installing more malware.
  • Your web browser’s homepage has changed unexpectedly, or new toolbars have appeared out of the blue. This is a sign your browser has been hijacked and is directing you to malicious third-party sites.
  • You are bombarded with ads. A classic indication of adware. While not too dangerous, this type of malware generates profits from ad clicks. Of course, none of the proceeds go to your pocket.
  • You can’t access personal files or system settings. Plus, your Mac displays messages about illegal content, fines you need to pay, etc. This could be a trojan horse or a case of ransomware — malicious software cybercriminals use to extort their victims.

Before we put up a fight, let’s make sure our enemy is real.

How to check your Mac for malware and remove it

If your Mac is showing any of the above signs, then running an antivirus scan is the best step to take. But before you let software fight this cybercrime, there are a few simple things you can manually do.


Check your Mac for unwanted applications

Malware often creeps into your system bundled with legitimate software. If you don’t remember installing an app or haven’t used it for a while, it probably shouldn’t be there.  

  1. Go to the Applications folder in Finder or use Shift + Command + A
  2. Look through the list and delete any programs you don’t recognize
  3. Don’t forget to empty the trash

Be sure to remove hidden files, too — check out the detailed guide on how to delete apps and their hidden files on a Mac.

Tip: you can control the sources your Mac installs software from. Check out Apple’s own recommendations.


Check browser settings and remove unknown extensions

Why? Because hijackers could divert your traffic and spy on you or steal your data.  


While the process is fairly similar in all browsers, it’s best to refer to your program’s help page for specific details. Here are the instructions for Safari:

  1. Open Safari and go to Preferences. Check the homepage address. If it looks suspicious, change it to the default option
  2. In Safari, open the Extensions tab and remove any you don’t remember installing


Clear your downloads folder

There is a chance malware could be hiding among other downloaded files, so a pre-emptive purge could save you from trouble. Move the files you need to other folders, delete everything else, and empty your trash.


Now we’ve exhausted the basic manual options, it’s time to let your antivirus software do its magic.


Run an antivirus scan

The process of virus detection on a Mac is straightforward:

  1. Install an antivirus app
  2. Open the app and run a full scan
  3. Wait until the scan is finished and check the results
  4. Remove detected threats and unwanted elements from your Mac

Would you like to know more about some advanced methods of removing malware on a Mac? We thought you would so here they are.


Bonus tips

So you’ve completed the steps above, but you want to leave no stone unturned and cure your Mac completely. We can help with that. Be brave, yet always exercise caution.


Stop malicious software using Activity Monitor

Sometimes you need to stop malware from running on your Mac before you can remove it.  

  1. Open Spotlight by pressing Cmd + Space (unless you set up a different shortcut) and start typing “Activity Monitor”. When the app pops up, click on it to run
  2. Look for specific malware app names if you know them or find apps with abnormally high CPU or memory usage
  3. Click on the X in the upper left area of the window to close the chosen apps
  4. Search the corresponding file names in Finder and delete them, then empty your trash


Get rid of suspicious login items

Malware often quietly starts working as soon as you log into your Mac. You can stop this from happening in a few simple steps.

  1. Click the Apple icon in the top menu and go to System Preferences
  2. Click Users & Groups and move over to Login Items
  3. Uncheck the boxes next to all suspicious items


Use Time Machine

It’s easy to perform a rollback of your system with this brilliant feature — provided you’ve been making regular backups on your device. Simply restore your Mac from a backup that was made before any signs of the virus were present on your machine. For details, consult  Apple’s official manual.


Create a new profile in macOS

Many viruses on Mac cling to a certain user instead of being device-specific. Miraculously, you can sometimes avert disaster by simply creating a new user profile. Follow the steps listed on Apple’s support page but remember: this measure is temporary, and you still need to get rid of the malware.


You did great: the threats have been identified and removed, and your Mac is healthy and happy. But before we start giving out medals, let us tell you a bit more about the different types of malware out there.

The most common types of malware on Mac

The more you know, the better your chances of choosing the right strategy when a security crisis comes.


Most people use the word “virus”, but it doesn’t cover every type of malicious software. That is why we’re using a word with a broader meaning: malware, or malicious software.  


Here are some examples of malware that can find their way onto your Mac:

Trojan horse

A trojan horse, or simply a trojan, is disguised as a legit application or file. You may think that you have downloaded a free wallpaper for your Mac, but you’ve picked up something far more evil instead. Hackers use trojans to attack computers or networks, encrypt your data and demand ransom, or create a backdoor into your Mac’s system for further intrusion.



Spyware watches your activity without your knowledge. The data it collects can later be used for blackmail, identity theft, or stealing your credit card details. One example of spyware is a keylogger that records the keystrokes of the victim’s computer. The malware’s creator can gain access to usernames, passwords, or banking information.



Ransomware encrypts your information, then demands a ransom in exchange for decrypting your files. As a rule, cybercriminals demand a  ransom be paid in cryptocurrency, which is almost impossible to trace.



Exploit is code that uses system vulnerabilities to break into your device and take control of it. You’ve probably heard of the Meltdown and Spectre vulnerabilities previously discovered in early 2018. These hardware flaws allow hackers to potentially steal all of a computer’s data.



The authors of this type of malware make their profits from the intrusive display of ads. They literally get a nickel every time a user clicks on an ad pop-up. Adware may not be so dangerous in terms of security, but constant pop-ups and redirections will interrupt your work and drive you nuts.


Last but not least, it’s good to know how your Mac can get infected, so you can avoid any future tricks from online scammers.

How Mac computers can get infected

Keep these in mind so you don’t give hackers the slightest chance.

  • Free downloads. We love new music and films, but many of us don’t like paying for them. Free downloads can often contain malware. It’s worth running a virus check on your Mac if you did choose to download that hot content.
  • Email attachments. Not only are spam emails annoying, but they can be dangerous too. Usually, malicious emails will urge you to open an attachment immediately. If something feels wrong, then don’t open the itt — instead, check every detail first. It could be an extra letter in the address or poor grammar that gives the scammer away. If you know the sender, get in touch and ask if they remember sending this email to you.
  • Apps from unreliable sources. Always download apps from trusted sources — the App Store or official websites. Spend some time reading reviews, research the developer, and be super careful when it comes to torrents and free software repositories.
  • Fake alerts on webpages. You might have heard of or even experienced fake Flash Player updates or fake virus alerts in your browser. Clicking on each notification and installing everything offered on suspicious web pages is a shortcut to infecting your Mac.

How to keep your Mac malware-free

Let’s be honest: Macs are as gorgeous and reliable as they come. These computers are so close to being perfect that we — their owners — are in awe and sometimes forget they’re not invincible. And even though macOS is built on rigid security principles, it’s the choices we make when using them that matter most. Let’s stay diligent and not let cybercriminals get the better of us.


At Clario, we’re always ready to help. We believe in digital safety for all, both off- and online. That’s why we’ve created our innovative app combining the latest cybersecurity technology with human intelligence and empathy. Get Clario, and let us take the burden of malware protection off your shoulders.

Read more:

Mac Security

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