Spyware is a broad category of malicious software designed to intercept or take partial control of a computer's operation without the informed consent of that machine's owner or legitimate user. While the term taken literally suggests software that surreptitiously monitors the user, it has come to refer more broadly to software that subverts the computer's operation for the benefit of a third party.
Spyware differs from viruses and worms in that it does not usually self-replicate. Like many recent viruses, however, spyware is designed to exploit infected computers for commercial gain. Typical tactics furthering this goal include delivery of unsolicited pop-up advertisements; theft of personal information (including financial information such as credit card numbers); monitoring of Web-browsing activity for marketing purposes; or routing of HTTP requests to advertising sites.
As of 2005, spyware has become one of the pre-eminent security threats for computers running Microsoft Windows operating systems. Some malware on the Linux and Mac OS X platforms has behavior similar to Windows spyware, but to date has not become anywhere near as widespread.
Spyware, "adware", and tracking
The term adware frequently refers to any software which displays advertisements, whether or not it does so with the user's consent. Programs such as the Eudora mail client display advertisements as an alternative to shareware registration fees. These classify as "adware" in the sense of advertising-supported software, but not as spyware. They do not operate surreptitiously or mislead the user.
Many of the programs frequently classified as spyware function as adware in a different sense: their chief observed behavior consists of displaying advertising. Claria Corporation's Gator Software provides an example of this sort of program. Visited Web sites frequently install Gator on client machines in a surreptitious manner, and it directs revenue to the installing site and to Claria by displaying advertisements to the user. The user's experience is that their computer begins displaying a large number of pop-up advertisements.
Other spyware behaviors, such as reporting on websites the user visits, frequently accompany the displaying of advertisements. Monitoring web activity aims at building up a marketing profile on users in order to sell "targeted" advertisement impressions. The prevalence of spyware has cast suspicion upon other programs that track Web browsing, even for statistical or research purposes. Some observers describe the Alexa Toolbar, an Internet Explorer plug-in published by Amazon.com, as spyware (and some anti-spyware programs report it as such) although many users choose to install it!
Remedies and prevention - Anti-spyware programs
As the spyware threat has worsened, a number of techniques have emerged to counteract it. These include programs designed to remove or to block spyware, as well as various user practices which reduce the chance of getting spyware on a system.
Nonetheless, spyware remains a costly problem. When a large number of pieces of spyware have infected a Windows computer, the only remedy may involve backing up user data, and fully reinstalling the operating system.
Many programmers and commercial firms have released products designed to remove or block spyware. is a good example of this and offers a free scan of your system for problems.
Text adapted from the , the free encyclopedia. All text is available under a copyleft (GFDL)
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