Spyware: What You Need to Know

It can turn your system against you, slow your browser to a crawl and inhabit your computer like some grotesque parasite. It can cling to your Windows registry with its grasping mandibles and sucking away its very life. And those are just the side effects of spyware -- those annoying, privacy-invading programs you'll spend the better part of the Thanksgiving holiday removing from your parents' computer.

A survey from California security company Trend Micro last week revealed that more than 87 percent of corporate end users are now familiar with the spyware threat -- 40 percent through personal experience. But a little more than half say they still don't know enough, and they'd like their IT departments to educate them.

We at Wired News run our IT over tin cans and used dental floss. Nevertheless, we offer these frequently asked questions as our contribution to the spyware education effort.

What is spyware?

The Anti-Spyware Coalition, (which includes heavyweights like Microsoft, EarthLink and Hewlett-Packard), says spyware is any application that impairs "users' control over material changes that affect their user experience, privacy or system security."

In plainer language, spyware consists of a host of programs that you likely wouldn't invite onto your computer if you knew what they would do once they invaded your machine. They are primarily software programs that can hijack your browser to send you to an advertiser's page or track where you surf on the internet so marketers can learn your interests and feed you pop-up ads.

Is spyware the same as viruses and Trojan horses?

Traditionally, viruses and Trojan horses have been considered a different type of malware, but the Anti-Spyware Coalition is attempting to lump all malware together to make it easier for lawmakers to legislate against it.

The coalition does not include viruses in this category, but it does include Trojan horses, which are usually installed on your machine without your consent and sit in the background quietly recording your keystrokes or sending copies of your files to a remote intruder over the internet. Keystroke loggers are generally not used by people who want to market to you, but by people who are interested in data like passwords or credit card numbers for financial gain or espionage.

How does spyware get onto my computer?

Spyware that delivers pop-up ads often comes hidden in free software downloads, such as games or browser plug-ins or toolbars. The makers of the software generally contract with advertisers to include a program in the download to feed you ads or give the advertiser information about you, such as which sites you visit.

The programs can also download automatically to your computer through websites you visit. Generally, you have to do something to install the program on your machine, but that something can be as simple as clicking a button that says "Close" to shut a pop-up window. This can activate an ActiveX control that installs the spyware on your machine. See below for tips on how to prevent spyware from infecting your computer.

How will I know if I have spyware on my machine?

You might notice an unusual number of pop-ups appearing on your screen, even when you don't go to the kinds of sites that generally deliver lots of pop-ups, such as gambling and porn sites. If pop-ups appear on your screen when you're offline, your computer is probably infected. Or you may find your browser homepage has mysteriously changed.

You don't need to wait for these signs, however, to see if you're infected. You can use a number of free software tools to search your computer for spyware, in the same way that antivirus software scans your hard disk for malicious code. Be careful to use a reputable tool, however. Some spyware masquerades as anti-spyware scanning tools but instead deposits spyware onto your computer. Before downloading such a tool, check sites like Spyware Warrior, which lists known rogue sites and programs that mimic helpful anti-spyware tools.

What does spyware do once it's on my computer?

Spyware installs itself and works behind the scenes. The least invasive, though no less intrusive, spyware simply delivers pop-up ads on top of your browser window while you surf. The more sinister ones hijack your browser and may change your homepage to an advertiser's page or track the sites you visit and send the information to an intruder. Spyware apps can also hog your computer's resources, such as the memory and hard drive, or cause your browser or computer to lock up or crash. Keystroke-logging spyware can capture passwords and credit card information to send to identity thieves and card criminals.

How do I get it off my machine?

Some of the same tools that help you scan for spyware can also help you remove it. When spyware installs itself on your machine, it leaves a sign of its presence in the Windows registry. Spyware scanners can find the programs and ask you if you want to delete them.

How do I prevent spyware from getting on my machine?

• Avoid downloading shareware and freeware.
• Don't open e-mail attachments from anyone you don't trust, and scan attachments with an antivirus tool before opening attachments from people you do trust.
• Use a spyware-monitoring tool like the free Spybot-Search & Destroy or PestPatrol ($30, with a free trial option) that can help prevent spyware from installing on your machine.
• Consider using an alternative browser such as Firefox or Mozilla rather than Internet Explorer. Spyware makers like to exploit Internet Explorer to download their wares to your computer.
• Adjust your browser's internet settings to High, or set it so only trusted sites are allowed to use ActiveX controls and Java applets and all others must ask you for permission.
• Avoid clicking buttons inside pop-up windows that invite you to close the window. Instead, close the window by clicking on the X in the corner of the window or by putting your cursor on the upper frame of the window where the title of the web page resides and hit Alt-F4. If you have a firewall on your machine, such as the free ZoneAlarm firewall, you can set it to prevent spyware from sending information about you out to the internet.