We categorized the adware into four groups, based on the primary behavior of each component:

• Ad injectors: This adware usually resides in the browser and can affect all operating systems.
• Browser-settings hijackers: This adware component can change computer settings to make the browser less secure.
• Utilities: This is a large and growing category of adware. Utilities are web applications that offer a useful service to users, such as PC optimization. These applications can inject advertising, but their primary purpose is to convince users to pay for the service. However, in many cases, utilities are nothing more than scams and provide no benefits to users.
• Downloaders: This adware can deliver other software, such as a toolbar.

High