Is your web browser acting oddly all of the sudden? Do funny windows pop-up showing you ads? Do your Google searches look weird? If so, you might have inadvertently installed some adware on your Mac. Starting in late 2014 I noticed a rash of Macs infected with adware. Adware is software that makes ads pop-up in your web browser. The good news is Malwarebytes for Mac, can be used to remove most adware as well as other types of malware from your Mac. Use these instructions to download a copy of Malwarebytes and scan your Mac.

MalwareBytes for Mac originally required OS X Mountain Lion (aka OS X 10.8) or higher, but later versions appear to require OS X Mavericks (aka OS X 10.9) or higher.

[UPDATE September 2017: Malwarebytes Anti-Malware for Mac has been renamed to Malwarebytes. Additionally, it’s been updated from version 1.x to version 3.0. Version 3.0 requires OS X 10.10 or higher. While Malwarebytes is still free to use, there is a paid version. This paid version offers real-time monitoring for malware and auto-updates. While you’re welcome to pay, the free version is adequate for many people. You would just have to open Malwarebytes periodically to initiate a scan and an update. When you install Malwarebytes you’re automatically given a 30-day trial version of the paid version. You can simply let this trial end and your version will automatically revert to the free version.]

1. Visit Malwarebytes’ web site
2. Click the big Free Download button to start to download the installer.
3. Open the Malwarebytes installer. Typically, you’ll find this in your Downloads folder.
4. Follow the on-screen prompts to install Malwarebytes on your Mac. The process entails clicking the Continue button a few times, agreeing to the license and then typing in your Mac user password to permit the installation. [If your Mac is using macOS High Sierra (aka OS X 10.13) or higher you’ll be notified that MalwareBytes System Extension was blocked. Click the Open Security Settings button and then click the Allow button to let this system software to be loaded.]
5. After the installation finishes, go to your Applications folder and double-click Malwarebytes to open it.
6. If you’re notified that you downloaded Malwarebytes.app from the Internet and asked if you want to open it, click the Open button.
7. Click the Scan Now button. Wait about 1-3 minutes for your Mac to be scanned.
8. If no malware is found click the OK button. If malware is found let Malwarebytes remove the files that it lists. You may need to type in your administrative user account password to give Malwarebytes permission to delete these files.
9. If malware is found you’ll likely be notified by Malwarebytes that a restart of your Mac is required so that it can completely remove all of the bits and pieces of the adware.
10. If malware was found and removed you may still need to change your web browser’s home page manually.