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Adware can install web browser extensions (add-ons) with the promise of ‘enhancing’ or ‘aiding’ your web surfing experience. However they are not required and you may not want them.
A common query is 'How did the adware get on my Mac?'. Adware is often bundled in to genuine Mac software by software download portals such as Brothersoft, CNET Download, and Softonic. When searching the web for the name of the software application you want these download portals often appear at the top of the results. These types of site can actually host the software you want, but the installer is re-packaged to include adware. When you run the download and install the software, if you don't watch carefully in the install wizard, the bundled adware gets installed too.
The screenshot below (click to enlarge) shows how a Mac download, that's in the top five downloads of CNET Download, provides an 'express' install option that includes adware and is selected by default.
Note: Shown above:  indicates a popular Mac download that testing has shown to contain adware.  shows the 'express' install option is pre-selected and will install adware.  shows an option to customize what is installed and de-select the adware.
We always recommend you download software direct from the vendors site or from a source the vendor's site links to if hosted external to their own site because of bandwidth. In all cases don't rush through the install and check what is being installed by choosing the 'custom' option. If you are in any doubt about a file that you downloaded send a sample to our lab for analysis. If you are not already running Sophos Anti-Virus on your Mac at home download a free copy here (it doesn't have any adware in it).
Once adware is installed on your Mac you may notice pop-up advertisements in your web browser and behind the scenes your browsing may be tracked to target ads to your computer. This article explains how to remove extensions/add-ons from your Mac. It covers three common web browsers - Safari, Firefox, and Chrome.
Applies to the following Sophos product(s) and version(s)
Not product specific
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