What is Spyware and How did it get on my computer?

Adware is software that displays advertisements on your computer. These are ads that inexplicably pop up on your display screen, even if you're not browsing the Internet. Some companies provide "free" software in exchange for advertising on your display. It's how they make their money.

Spyware is software that sends your personal information to a third party without your permission or knowledge. This can include information about Web sites you visit or something more sensitive like your user name and password. Unscrupulous companies often use this data to send you unsolicited targeted advertisements.

Is Your PC Affected by Spyware?

The main problem that most people notice with either kind of program is that they cause performance issues with their computers. For example, Internet Explorer might not work properly any more, your computer might hang more frequently, or your computer might slow down significantly. Removing spyware successfully is difficult enough to make preventing it in the first place a priority.

Unauthorized adware and spyware usually install on your computer covertly by using one of two methods:

• Tricking you into clicking a link that installs it. Links to spyware can be deceptive. For example, a website that's trying to push spyware onto your computer might open a window that looks like a Windows dialog box, and then trick you by installing when you click a Cancel button to close the dialog box. Sometimes, spyware pushers will put a fake title bar in an empty window, and then install spyware when you try closing the window.
• Installing freeware that includes it. For example, you might install a free file-sharing program that surreptitiously installs spyware on your computer. File-sharing programs can be a major conveyor of adware.

Once installed, spyware can transmit your personal information and download advertisements 24 hours a day. It can also hijack your browser settings, such as your home page or search page.

Prevent Unwanted Installation

Companies pushing adware and spyware are relying on two things: your desire for free software and your gullibility. I've had two friends bring me their computers after they were seriously infected with adware. In one case, the culprit was my friend's craving for free file-sharing software. His desktop was a mess with countless icons for programs that he downloaded from the Internet. I was aghast. What he didn't realize is that he gave implicit permission to install adware. He knows better now.

My other friend isn't a freeware glutton. Instead, she has a habit of clicking the Yes or OK buttons on every dialog box she sees. Even suspicious-looking dialog boxes that don't pass close scrutiny. Of course, when a dialog box pops up asking if it's OK to install a new program, she clicks the Yes button.

The lesson that you can learn from my friends will help you prevent the installation of most adware and spyware:

• Make sure the programs you install don't contain adware. Many freeware programs do include adware. It's how the publishers make their money. If you're not sure, read the license agreement carefully (these are usually shown directly or through links as part of the installation process). Also, check the publisher's Web site very carefully. If you're still not sure, search Google Groups for the name of the program and the keywords adware or spyware. If you don't find any postings about it, then you're probably OK.
• Install a pop-up blocker to prevent adware and spyware pop-up windows. Much spyware installs after you click a deceptive link in a pop-up browser window. Install a pop-up blocker, and you won't even be tempted to click those links. My two favorite pop-up blockers are completely free. The first is the Google Toolbar. The second is the new MSN Toolbar. Pop-up windows are annoying time wasters anyway, so you'll thank yourself later. If you're a Windows XP user, Service Pack 2 (released August 2004) includes a number of great security features, as well as a pop-up blocker for Internet Explorer.
• Don't unwittingly install adware or software. If you do click what seems like a innocuous link, and then you see a dialog box  don't click the Yes button to install the software. In this example, I was expecting to install a program from Microsoft so I feel safe. If in doubt, however, do not proceed. This dialog box is your last line of defense, and you should only install programs from the Internet that you chose to install. This is akin to giving someone your credit card number who calls you at home. It's a different story if you called them. Also, instead  of clicking the NO button, press ALT-F4 on your keyboard to close the window.  Often, NO means YES with pop-ups.

Spyware scanners and some virus scanners with spyware signatures can help combat spyware. However, the best strategy is to be discriminating about what you choose to download and install.

Check Your Computer

If you're even thinking about scanning your computer for adware and spyware, then you're probably experiencing some of the symptoms I described earlier in this article. Those include instability, performance problems, or possibly a hijacked Web browser.

There is software specifically designed for detecting spyware and adware, and helping you remove it. The one with which I'm most familiar is Ad-aware from Lavasoft. This is the program that I recommend to most of my friends. A freeware version is available for use by individuals at home. A commercial version is also available for use in corporate environments. A program like Ad-aware finds adware and spyware on your computer and then removes them.

You can find more adware and spyware removal tools at the Spyware Protection and Removal guide. This Web page includes links to popular spyware removal programs, as well as a number of useful articles. If you're not going to use a popular program like Ad-aware, however, search Google Groups for the name of the program you do choose. Some spyware removal software can cause as many problems as it fixes, and you want to find out about these problems before using unproven software.