3 Signs Your Mac Is Infected With a Virus (And How to Check)

Sadly, Macs aren’t the safe haven they once were. Yes, infections are still less common on Macs than on Windows machines, but they do happen.


If your Mac is acting weird—maybe you see adverts you can’t explain, or your system is unreasonably slow—the problem could be malware.

Keep reading to learn how to recognize the signs of a virus on your Mac and how to scan your system to find it.


Can Macs Get Viruses?

Despite the seemingly common belief that Macs are immune from viruses, they can still become infected.

Indeed, Mac malware can come in many forms. Here are some examples that have generated headlines:

  • Silver Sparrow: Silver Sparrow targets Macs with an M1 chip. It uses the macOS Installer JavaScript API to execute commands and is known to contact its servers once per hour. Experts worry that it’s prepping a major attack in the near future.
  • Pirri/GoSearch22: The first malware to target M1 Macs was Pirri/GoSearch22. The virus itself is adware—it inserts ads into places where they wouldn’t normally appear.
  • Thief Quest: First seen in 2020, ThiefQuest steals data from files in folders on your machine. The malware itself is disguised as ransomware, except no ransom is ever demanded.
  • LoudMiner: This malware is a malicious crypto-mining app. It was distributed via a cracked version of the popular Ableton Live app.

How Do You Know If Your Mac Is Infected With a Virus?

All of these infections have one thing in common: they infect Macs through processes outside of the App Store. In some cases, pirated software is to blame; in others, it’s software from sources that shouldn’t have been trusted. Downloading too many third-party apps is one of several mistakes that beginner Mac users make.

Simply put, if you never install software from outside the Mac App Store, you don’t have much to worry about. Sure, there are some browser-related exploits from time to time, and Java is an ongoing concern, but if macOS and browsers are up to date, such infections are pretty unlikely.

And if you do install software from outside the Mac App Store, but are careful to research software before installing it (Googling for a review and finding an official download), you also don’t have anything to worry about.

On the other hand: if you’ve pirated Mac software or installed plugins at the request of a site offering pirated movies, you might have problems. Have you used a tainted USB drive or downloaded a sketchy email attachment? Viruses can spread in lots of unexpected ways like this.

So, is your Mac infected? Let’s look at the signs.

1. Unexpected Ads and Pop-Ups

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Adware is becoming an ever-bigger problem on the Mac platform. If you see ads in places they previously didn’t show up, there’s a good chance you’ve installed something you shouldn’t. This is particularly true if you get pop-up ads even when you’re not browsing the internet.

2. Your Mac Is Slow for No Reason

Some Mac malware makes your Mac part of a botnet, which is a global network of computers used for all sorts of things. If your Mac is infected, it could be helping to perform a DDoS (Distributed Denial of Service) attack on a website, mine Bitcoins, or complete any number of tasks that take up CPU power.

This is a possibility if your Mac is constantly slow, even if you don’t have any programs running. And remember, if malware isn’t the problem, you need to work out what is causing your Mac to run slowly.

3. Malware Scanner Confirms Infection

Think your Mac might be infected? It’s time to check. Here are a few free programs you can use to scan your Mac and find out about any infections:

  • Bitdefender Virus Scanner: This app is free. It won’t delete infections for you, but it will point out where to delete them using the Finder.
  • Malwarebytes for Mac: Malwarebytes has been one of the leading names in the anti-malware world for many years. Its Mac app can scan your entire system in less than 30 seconds and will remove adware and potentially unwanted programs.
  • ClamXAV: ClamXAV is the Mac version of ClamAV, a popular open-source malware detection tool. It’s well worth a look.

If none of these tools come up with anything, it’s extremely unlikely that your Mac is infected. You can also use an online virus scan tool. As always, check the app reviews in the App Store to help you make a decision.

Of course, there are other apps out there—if you know of something better, let us know on Twitter. And if you’re still curious whether or not antivirus software is necessary, trust us when we say you do, especially if you aren’t diligent.

How to Check for a Virus on Your Mac

Your Mac has defenses in place that should keep you safe from malware, though, like all such measures, they’re not completely foolproof. Here are a few reasons why you don’t need to worry (much):

Gatekeeper

Gatekeeper stops uninformed users from installing potentially unsafe software. By default, this means anything not from the Mac App Store, but you can also configure it to block apps from unknown developers.

Of course, many Mac users disable Gatekeeper completely so they can run whatever software they like, including things they’ve compiled themselves. The hope is that well-informed users will research the apps they run before installing them.

Sandboxing

Apps installed through the Mac App Store have very limited access to the broader system, a limitation intended to stop one app from messing up your entire system.

XProtect

XProtect is the anti-malware program you didn’t know you had. In fact, XProtect has been a part of macOS since 2009, but this program isn’t like Windows antiviruses—it’s completely invisible to most users.

You can’t open the program and run a scan yourself, and you can’t manually install updates. But if your Mac is infected with a known virus, odds are this program will eventually notify you. It also stops you from opening infected files.

If this doesn’t do the job, try one of these great paid Mac antivirus apps.

You should now recognize whether your Mac has been infected with malware. However, prevention is better than cure, as they say. So, if you want to ensure you never have to worry about malware on your Mac, you should install a high-quality antivirus suite.

Once you install a solid antivirus app (and assuming you make an effort to stay safe online), it’s unlikely that you will ever encounter malware on your Mac.

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