How Does Adware Work?

By Gigi Starr

What Is Adware?

Adware are the advertisements that appear in pop-ups or banners on computer screens. Clicks on the ads produce a monetary payoff for the software producers. Unlike malware or spyware, adware many times is loaded onto the computer with the user's permission. Information about the software is usually included in the EULA (end user license agreement), which must be read carefully before being downloaded (see Resources below).

How Does Bad Adware Work?

Bad adware usually enters a user's computer during routine Web surfing. Programmers create software that runs like a virus or Trojan horse. For example, people may download a peer-to-peer file sharing client that contains hidden adware. The ads begin to show up after the program files are loaded onto the system. After that, the program may plant tracking cookies, keyloggers (programs that copy information inputted by keyboard) or perform intrusive hard drive scans. If left undetected, a malicious adware program may transmit credit card numbers, passwords, pictures and other sensitive information to unscrupulous people who may take advantage of this information to steal from the user.

How Can I Fight Malicious Adware?

The best way to defeat bad adware is to run a firewall at all times while surfing the Web. A firewall constantly detects any program that seeks to transmit or take information from the Internet. When a firewall senses a download that might have certain known virus attributes, it locks up access to the system and doesn't allow the download to take place. If there's already adware on your computer, there are free or low-cost programs that can help. Two popular programs are AdAware and SpyBot Search and Destroy (see Resources below). Many people run these in conjunction with an anti-virus program for the best results. It's often impossible to uninstall malicious adware through normal means, but these programs are equipped to clean up the most well-known culprits.