Excruciating extensions
Most browsers support extensions – software add-ons, such as allowing you to save passwords. Sometimes clicking on the wrong link results in malicious extensions being installed. Usually these are designed to show adware – pop-up advertisements which are annoying and can slow down your system. While in Safe Mode, open Safari, then click Safari > Preferences. In the new window, click Extensions to see what you have installed. If you don’t recognise an extension, clear the checkbox to disable it. Click More Extensions to browse legitimate extensions for Safari. Install both Adblock Plus (adblockplus.org) and Ghostery (ghostery.com) to avoid harmful links and prevent websites from tracking you easily. Log out and repeat for each user on your Mac.