How to Get Rid of a Virus on a Mac

Understand the signs of malware infection and clean up your system

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Updated on May 24, 2021

Although Macs are less vulnerable to viruses than PCs, they're not immune to malware, adware, and other scourges. If you suspect some kind of malicious program has infected your system, here's how to identify the issue and clean up any OS X or macOS computer.

How to Know If Your System Is Infected

Your Mac's behavior offers clues that it's been infected. For example, the machine runs slower than usual, its fans run constantly, it stops responding, or it suddenly reboots.

If you find browser extensions, toolbars, or plug-ins you didn't install, notice third-party applications you never asked for, or your browser's settings have mysteriously changed, malware is probably the culprit.

An adware infection reveals itself with unexpected ads and pop-ups on your desktop, browser home page, or other websites you visit.

In general, consistently odd, unexplained behavior, especially in relation to internet activity, points to a malware infection.

Types of Infections

A variety of bugs and malicious software can infect your Mac, but the removal process is generally the same. Understanding the terms can be helpful.

Malware

Malware, short for malicious software, is any software that intentionally harms a computer or performs user-hostile actions. It's a catch-all term that includes:

Adware, which displays unwanted ads.
Spyware, which tracks your behavior.
Ransomware, which encrypts your user files and demands payment to decrypt them.
Trojans, which seem innocent on the surface but contain hidden trouble.

Potentially Unwanted Software (PUPs)

A potentially unwanted program might perform some valuable function, but it comes bundled with unwanted side effects. A PUP might change your home page and search engine, add malware to your computer, or steal your credit card information when you pay for the application's dubious "service."

Often, people install PUPs because they were tricked by dishonest ads or clicked through installer steps without reading them. PUPs are the most common type of malware found on Macs.

Viruses

A virus spreads from computer to computer like a disease, attaching to other files to infect more and more devices. Viruses use the internet, local network connections, or USB drives to propagate. There are a few steps to take to clean up your system and remove unwanted malware for good.

Mac viruses are virtually unheard of, but the term has become a generic word for describing any type of malware infection.

Kill Running Processes

The first step in tracking down and eliminating a bad actor in your system is closing apps and processes. Here's how:

Open the Activity Monitor.
Look for unfamiliar applications.

If you're not sure what you're looking for, consult Malwarebytes' list of current viruses and malware for the Mac, or check out a list of older bugs.
If you find malware listed in the Activity Monitor, select the application, and select the Quit Process icon on the left side of the top menu (it looks like a stop sign with an X).
When asked if you're sure you want to quit this process, select Quit.

Find and Uninstall the Malicious Program

Next, it's time to find and uninstall the unwanted program. Even if you didn't see any malware in the Activity Monitor, still go through this process.

Open the Applications folder.
If you know the name of the malware, find the application in the list. If you aren't sure of its name, look for any suspicious program you don't remember installing.

Pay attention to new folders and recently installed applications.
Find the malware's application folder. Right-click the folder and select Move to Trash, or drag it to the trash can.
Empty the trash can.

Remove Login Items

Login items are programs that launch automatically when your computer boots. If you see an application's window as soon as you log in to your Mac, that's a login item. Malware often sets itself up as a login item so it can relaunch every time your computer boots. Here's how to find and delete them:

From the Apple menu, select System Preferences.
Select Users and Groups.
Select the Login Items tab.
If you see something on this list you don't recognize, or you see known malware, select the item and choose the Remove (minus sign) icon on the bottom.

Clean Your Browsers

Many forms of adware and malware install some sort of browser extension or change your browser settings in some way. Most commonly, they change your home page, search engine, or new tab page. Here's how to make sure your browsers are clean.

In Chrome, select the More icon (three vertical dots).
Select Settings.
Click Extensions.
Examine your extensions and make sure you know what each one does.
If you find an extension that shouldn't be there, select Remove.
Next, look at your browser and internet preferences. In Chrome, go to Settings > Search Engine and make sure the search engine and browser settings are what you want. If not, select Manage Search Engines and remove any unwanted search engines.

In Chrome, also go to Settings > Default browser and make sure your preferred browser is selected.
Repeat this process for every web browser installed on your computer.

Run a Malware Scan

To make sure you've removed every piece of malicious software, run a trusted malware scanner such as Malwarebytes. Malwarebytes scans your system for known malware. If any dangerous files are found, they're transferred to the Quarantine section, where they can be successfully deleted.

Visit the Malwarebytes website, and select Free Download.

In the Malwarebytes free version, you must run the software manually to remove adware and malware. The paid version automatically blocks malware that tries to access your device.
From the Downloads folder, select the PKG file.
An Install Malwarebytes for Mac window opens. Select Continue a few times to advance.
Select Agree to agree to the license terms.
Select Install, enter the local administrator credentials, and select Install again.
Select Close when the installation is complete.
Select Get Started.
Select Personal Computer and then choose Use Malwarebytes Free.
Enter your email address if you want to receive updates, and then select Open Malwarebytes Free.
Select Scan to begin scanning for malware.
When the scan completes, you'll see a list of found malware or a message stating your Mac is free of malware.
Select Quarantine.
Malwarebytes removes the problematic files. You might need to restart your computer.

Extra: Tips for Staying Malware-Free

Although macOS comes with some built-in security features, changing your browsing habits is an important component of staying malware-free. Here are a few tips:

Avoid untrustworthy downloads, especially torrents from sites such as BitTorrent.
Always be aware of what you're installing. Read every word in an installer to avoid inadvertently agreeing to install unwanted software.
Keep your software up to date. In particular, always download the new versions of macOS, especially the security updates.

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