- Virus : A program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can also replicate themselves. All computer viruses are manmade. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems. http://www.webopedia.com/TERM/v/virus.html
- Spyware: Any software that covertly gathers user information through the user's Internet connection without his or her knowledge, usually for advertising purposes. Spyware applications are typically bundled as a hidden component of freeware or shareware programs that can be downloaded from the Internet; however, it should be noted that the majority of shareware and freeware applications do not come with spyware. Once installed, the spyware monitors user activity on the Internet and transmits that information in the background to someone else. Spyware can also gather information about e-mail addresses and even passwords and credit card numbers. http://www.webopedia.com/TERM/s/spyware.html
- Adware: A form of spyware that collects information about the user in order to display advertisements in the Web browser based on the information it collects from the user's browsing patterns. http://www.webopedia.com/TERM/a/adware.html
- Phishing: The act of sending an e-mail to a user falsely claiming to be an established legitimate enterprise in an attempt to scam the user into surrendering private information that will be used for identity theft. The e-mail directs the user to visit a Web site where they are asked to update personal information, such as passwords and credit card, social security, and bank account numbers, that the legitimate organization already has. The Web site, however, is bogus and set up only to steal the user's information. For example, 2003 saw the proliferation of a phishing scam in which users received e-mails supposedly from eBay claiming that the user's account was about to be suspended unless he clicked on the provided link and updated the credit card information that the genuine eBay already had. Because it is relatively simple to make a Web site look like a legitimate organizations site by mimicking the HTML code, the scam counted on people being tricked into thinking they were actually being contacted by eBay and were subsequently going to eBay's site to update their account information. http://www.webopedia.com/TERM/p/phishing.html
- Rootkits: A rootkit is a set of software tools intended to conceal running processes, files or system data from the operating system. Rootkits have their origin in relatively benign applications, but in recent years have been used increasingly by malware to help intruders maintain access to systems while avoiding detection. Rootkits exist for a variety of operating systems, such as Linux, Solaris and versions of Microsoft Windows. Rootkits often modify parts of the operating system or install themselves as drivers or kernel modules. http://en.wikipedia.org/wiki/Rootkit
- Worms: A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other nodes (computer terminals on the network) and it may do so without any user intervention. Unlike a virus, it does not need to attach itself to an existing program. Worms always harm the network (if only by consuming bandwidth), whereas viruses always infect or corrupt files on a targeted computer. http://en.wikipedia.org/wiki/Computer_worm
- Trojan Horse: In the context of computer software, a Trojan horse is a program that contains or installs a malicious program (sometimes called the payload or 'trojan'). The term is derived from the classical myth of the Trojan Horse. Trojan horses may appear to be useful or interesting programs (or at the very least harmless) to an unsuspecting user, but are actually harmful when executed. http://en.wikipedia.org/wiki/Trojan_horse_%28computing%29
- Keyloggers: Keystroke logging (often called keylogging) is a diagnostic used in software development that captures the user's keystrokes. It can be useful to determine sources of error in computer systems and is sometimes used to measure employee productivity on certain clerical tasks. Such systems are also highly useful for law enforcement and espionage—for instance, providing a means to obtain passwords or encryption keys and thus bypassing other security measures. However, keyloggers are widely available on the internet and can be used by anyone for the same purposes. http://en.wikipedia.org/wiki/Keylogger
- PUP's: PUP is an acronym for Potentially Unwanted Program. PUP or PUPs is a term used to describe unwanted programs such as Trojans, spyware and adware, along with other malware which may compromise your privacy. Some antivirus and PC security software packages, like McAfee VirusScan, will scan for and protect your system against PUPs. The term PUP was first used by persons at McAfee's Avert research lab to avoid any legal issues that may arise from calling these types of applications "spyware". http://www.webopedia.com/TERM/P/PUP.html
- Pharming: Pharming is a hacker's attack aiming to redirect a website's traffic to another (bogus) website. Pharming can be conducted either by changing the hosts file on a victim's computer or by exploitation of a vulnerability in DNS server software. DNS servers are computers responsible for resolving Internet names into their real addresses — they are the "signposts" of the Internet. Compromised DNS servers are sometimes referred to as "poisoned". The term pharming is a word play on farming and phishing. Antivirus software and spyware removal software cannot protect against pharming. http://en.wikipedia.org/wiki/Pharming