Spyware and Adware, and How They Interact

The internet is like a petri dish in a biology lab. On average, every system gets "sniffed" by a port sniffing attack, or by an attempted infection by a malicious program roughly once every 10 to 15 seconds.

One of the most prevalent categories of malicious software (malware) is spyware, and its close cousin, adware. Both types of software will, optimally, install themselves on a user's hard drive without the user being aware of their function, and without their permission. For most users, the first sign they've been hit by spyware is that their machine becomes less responsive. Spyware is usually tacked on to graphics, animations and links on web pages.

Most spyware is used ostensibly for "market research" - it tracks what web sites you hit, and what programs you use, and transmits it back to a vendor that tabulates the results. Some spyware is much more malicious than that, acting as a ferret for passwords and credit card information, or logging all keystrokes entered and transmitting it when network traffic is slow.

Adware is software that persistently displays ads, usually when a web site URL shows up in your browser's web history. If you've ever had a situation where your computer has been inundated with pop up browser windows, you've been hit with adware. An earlier form of adware used the Windows Message functionality to open a port that let computer broadcast network messages that had to be clicked to close them.

Many sorts of adware work in conjunction with spyware, and the two get conflated a lot in terms of what they do. Indeed, some adware is only triggered when spyware indicates a subject of interest has come up. This is, normally, targeted advertising...if by targeting, the advertiser thinks in terms of "Make someone aware of my product by swearing to never, ever buy it." Indeed, some advertisers have claimed that adware pushing their product was promulgated by corporate rivals!

There are several software suites out there that will sweep your computer for adware and spyware. The three most commonly used (because they're free) are AVG-AntiSpyware, Ad Aware, and Spybot Search and Destroy. It's recommended that you run all three of them, regularly - roughly once a week or so, to keep your system running in tip top shape. Failing to do this can force you to scrub your hard drive down and reinstall your operating system, which is never fun.