Types of Spyware

Many Spyware programs specialize in performing one task-displaying ads, collecting data, changing browser settings, etc. - and can be easily categorized. However there are a large number that perform a variety of different actions and are harder to label. Still, a vocabulary for the different types of Spyware threats has grown useful within the industry and may help home users detect and diagnose threats.

Adware

Displays unwanted or intrusive advertisements, or facilitates the delivery of unwanted ads. The Adware label covers a broad range of threats that can display ads in browser windows, open commercial Web sites, and collect data for market research.

Browser Helper Object (BHO)

BHOs are not inherently dangerous. They are DLL files that are executed by Internet Explorer. Add-in toolbars and sidebars are BHOs, and many of them are completely benign, like the Google toolbar. However, a great number of BHOs function as Spyware, tracking Web usage, recording private data and even displaying ads.

Browser Hijacker

Changes Web browser settings like homepage, search page, error page, and Favorites/Bookmarks. Browser hijackers are a common form of Spyware, affecting millions of computers across North America alone. If your homepage changes unexpectedly or your search results seem strange, you may have a browser hijacker.

Dialer

Programs that access a user's phone line via a phone-connected modem. Dialers can make unauthorized calls to pay-per-minute phone services, costing the user hundreds of dollars in phone charges.

Downloader

Downloads and installs unsolicited files or programs, often without notifying the user or requesting permission. Downloader programs are especially dangerous because they allow any type of file, including worms and viruses, to be downloaded onto the user's computer

Exploit

Exploits a security vulnerability in another program, often to allow an intruder to remotely access the user's computer. A threat is often classified as an exploit if it is known to exploit a vulnerability, but its other effects are unknown.

Flooder

Sends massive amounts of data to a computer or network in an attempt to overload and disable a network/Internet connection.

Keylogger

Records keystrokes into a log file and may transmit or e-mail the file to an intruder. Keyloggers can record passwords and logins, allowing intruders to access passworded programs and web sites, including online banking accounts. Most keyloggers log ALL keystrokes.

Malware

A generic term for software designed specifically to do damage-"malicious software." Malware and viruses seem similar, but Malware is typically not self-replicating or designed for PC-to-PC distribution.

Remote Administration Tool (RAT)

Allows a remote intruder to access a user's PC and perform unwanted actions ranging from basic data collection to file erasure and uploading, restart and shutdown, and even hard-drive formatting. Similar to so-called "backdoor" applications, RATs give intruders easy access to a PC.

Spyware/Surveillance

Designed to collect data for a variety of purposes, true Spyware (or surveillance) applications record personal or private information and transmit it to a third party. Often this data is used for market research and advertising, but more malicious Spyware programs attempt to steal passwords, logins, banking details and credit card information.

Trackware/Data Miner

Tracks the user's Web usage, Web searches, or general computer use. Cookies are one kind of data miner, and although most are harmless, some attempt to collect private information.

Related

They're not Spyware, but the following are commonly associated with many Spyware threats.

Trojan

Trojan horse programs take their name from the mythical wooden horse that carried hidden Greek soldiers into Troy. These programs contain hidden functionality, often posing as useful applications yet performing Spyware or Adware functions, or allowing remote access.

Worm

Worms are self-replicating, fast-spreading Internet threats that are more akin to viruses than Spyware. They differ from viruses in that they can replace entire files on the host computer. Both viruses and worms attempt to spread to as many computers as possible, using e-mail, the Internet, and file-sharing networks as methods of distribution.