Mac malware is rare, but it does exist. Whilst it is unlikely that a Mac can get a virus or malware, it's not impossible. Anything device that connects to the internet can be subject to abuse. Every so often a new piece of Mac malware hits the headlines and it can cause havoc. Historically, Macs haven't been targeted by malware authors, mainly because they were considered niche. More people own PCs, and therefore targeting a PC means targeting a larger audience.

However, the Mac has become more popular in recent years, and as a result people with malicious intent have started to target them more frequently. According to Malwarebytes, there's been a 230% increase in Mac malware since July 2016.

Malware is different from other forms of malicious software such as viruses. Malware doesn't attempt to get into your machine without your knowledge like a virus does – it is malicious software disguised as legitimate software. Perhaps you see an advert on a website, or you receive an email, either of which can trick you into installing it as you would any other program. When it is installed, it can then slow your computer down, create pop ups, or generally be an annoying blot on your life!

LOOKING FOR UNKNOWN APPS:

1. Quit the web browser you're using by pressing Command and Q on your keyboard, or right clicking on the icon of the browser and choosing Quit.
2. Go to your Downloads folder and drag any install files, or files that you don't recognise, into the Trash.
3. Empty the Trash by right clicking and choosing 'Empty Trash'

If you suspect that you've already installed malware on your Mac, follow these steps to remove it:

1. If the app is open, check the name of the app.
2. Move or close the app window
3. Open the Utilities folder (Command-Shift-U)
4. Open Activity Monitor
5. Choose All Processes
6. Look for the name of the app from step one, or an app that you don't recognise, and click Quit Process.
7. Open the Applications folder and locate the app you just Quit Process for.
8. Drag the unwanted app to the Trash.
9. Empty the Trash.

Now that you've checked and removed any malware from your Mac, you'll want to ensure that your Mac doesn't get any malicious software in the future. Use the tips below to keep your Mac safe from malware.

1. Ensure your Mac is up to date. Open the App Store app and click Update All.
2. Turn on automatic updates. Open System Preferences and click App Store. Now select the option Automatically Check for Updates. Make sure both Install macOS Updates and Install System Data Files and Security Updates are also both selected.
3. Make sure your Mac only allows apps from trusted developers. Click on System Preferences > Security and Privacy and General. Check that the option under Allow Apps Download From is set to either Mac App Store or Mac App Store and Identified Developers. If it is set to Anywhere, then click on the Lock icon, enter your password, and change it to either Mac App Store or Mac App Store and Identified Developers.

INSTALL MALWAREBYTES:
Malwarebytes https://www.malwarebytes.com/mac/

Is free and is a good tool to inspect the PC for any malware.
Also make sure you have installed a good anti-virus system - Norton Internet Security is one of the best.