Spyware

Spyware is computer software that is installed surreptitiously on a personal computer to intercept or take partial control over the user's interaction with the computer, without the user's informed consent.

While the term spyware suggests software that secretly monitors the user's behavior, the functions of spyware extend well beyond simple monitoring. Spyware programs can collect various types of personal information, such as Internet surfing habits, sites that have been visited, but can also interfere with user control of the computer in other ways, such as installing additional software, and redirecting Web browser activity. Spyware is known to change computer settings, resulting in slow connection speeds, different home pages, and/or loss of Internet or functionality of other programs. In an attempt to increase the understanding of spyware, a more formal classification of its included software types is captured under the term privacy-invasive software.

In response to the emergence of spyware, a small industry has sprung up dealing in anti-spyware software. Running anti-spyware software has become a widely recognized element of computer security best practices for Microsoft Windows desktop computers. A number of jurisdictions have passed anti-spyware laws, which usually target any software that is surreptitiously installed to control a user's computer. The US Federal Trade Commission has placed on the Internet a page of advice to consumers about how to lower the risk of spyware infection, including a list of "do's" and "don'ts.

The first recorded use of the term spyware occurred on October 16, 1995 in a Usenet post that poked fun at Microsoft's business model.^[2] Spyware at first denoted hardware meant for espionage purposes. However, in early 2000 the founder of Zone Labs, Gregor Freund, used the term in a press release for the ZoneAlarm Personal Firewall.^[3] Since then, "spyware" has taken on its present sense.^[3] According to a 2005 study by AOL and the National Cyber-Security Alliance, 61 percent of surveyed users' computers had some form of spyware. 92 percent of surveyed users with spyware reported that they did not know of its presence, and 91 percent reported that they had not given permission for the installation of the spyware.^[4] As of 2006, spyware has become one of the preeminent security threats to computer systems running Microsoft Windows operating systems. Computers where Internet Explorer (IE) is the primary browser are particularly vulnerable to such attacks not only because IE is the most widely-used,^[5] but because its tight integration with Windows allows spyware access to crucial parts of the operating system.^[6][5]

Before Internet Explorer 7 was released, the browser would automatically display an installation window for any ActiveX component that a website wanted to install. The combination of user naiveté towards malware and the assumption by Internet Explorer that all ActiveX components are benign, led, in part, to the massive spread of spyware. Many spyware components would also make use of exploits in Javascript, Internet Explorer and Windows to install without user knowledge or permission.

The Windows Registry contains multiple sections that by modifying keys values allows software to be executed automatically when the operating system boots. Spyware can exploit this design to circumvent attempts at removal. The spyware typically will link itself from each location in the registry that allows execution. Once running, the spyware will periodically check if any of these links are removed. If so, they will be automatically restored. This ensures that the spyware will execute when the operating system is booted even if some (or most) of the registry links are removed.

Trend Micro Inc. defines Spyware as "[...] a program that monitors and gathers user information for different purposes.."^[7]

McAfee Inc. defines Spyware as "Software that transmits personal information to a third party without the user's knowledge or consent.