Antivirus Program

An antivirus program is a piece of software designed to detect and destroy computer viruses. Most of the modern ones also detect and destroy other forms of malware as well as viruses. See the Antivirus Programs page for more information. See also Internet Security.

Backdoor

A backdoor is a utility that enables your computer to be remotely administered over a local network or the Internet. They are often installed by Trojans. Once installed there is the potential for a hacker to use your computer for his own purposes. This could be anything from accessing your data to using your computer as part of a botnet to send spam email, or carry out denial-of-service (DOS) attacks on corporate networks.

Botnet

This is an acronym formed from two words - RoBOT NETwork. A computer infected with malware that installs a backdoor utility enabling remote administration can be used by a hacker as a 'zombie' or 'bot' computer - part of a botnet. These networks of computer can be used for all sorts of criminal activity such as mass spam email campaigns, infecting other computers with malware or denial-of-service (DOS) attacks on corporate networks.

Browser Plug-in

A Browser Plug-in is an after-market utility with additional functionality not included with the web browser. These might be toolbars with a range of functions, ActiveX controls or utilities to allow multimedia applications to play. Plug-ins are available for Internet Explorer, Firefox and other common Web Browsers. As well as performing useful functions, some plug-ins can also perform unwanted activity - installing adware and collecting data about browsing habits, for example.

Cookie

A piece of data put on your computer hard disk by a website. When you re-visit that website the data is retrieved from the cookie and the website 'remembers' your settings. These are typically things like login information, user preferences, shopping cart selections and so on. Most of these are harmless and actually make your browsing experience better, but check the section on Tracking Cookies...

Data Miner

A category of spyware program that collects data from your computer, including websites you visit and data that you enter into forms. Usually hidden and working without your knowledge.

Dialer

A program that tries to dial out to a premium rate telephone number using your modem. These are becoming less common as fewer people connect to the Internet with a modem nowadays.

DOS

No, not the DOS operating system that came before Windows. In this context it means Denial Of Service. This is a mass attack on a corporate network by overloading it with traffic and effectively shutting the service down. These attacks typically come from botnets, or networks of 'zombie' computers, under the control of a hacker. He may have a grievance against the target organization, or may be getting paid by an unscrupulous competitor.

Email Worm

A category of worm that uses email to spread. See worm.

Firewall

A Firewall is an integrated collection of software programs designed to protect a computer, or network, from electronic attack by hackers or malicious software.

Heuristic Scanner

Heuristics is a general term used to describe the generic scanning method which is useful for detecting new malware for which specific signatures have yet to be established. The specific scanner with the virus/ malware definition files will not detect these until an update with new signatures is available.

The specific heuristic methods used vary between manufacturers and some have better detection rates and fewer false alarms than others. They typically look for suspicious attempts to call system commands such as 'format disk' or 'erase file'.

Most of the major antivirus brands use a heuristic scanner to complement the specific scanner. See the antivirus page for more information.

Key Logger

A software program that captures and keystrokes, screenshots and mouse clicks. Legitimate programs of this type can be used to study how users interact with computers, or by employers to monitor productivity. Malicious keyloggers are spyware programs that capture keystrokes and transmit them to a hacker without the knowledge of the computer user.

Quarantine

A safe area of your computer that an Antivirus program moves infected files to if it is unable to repair them. You can leave them in quarantine until they can be cleaned at a later date, or delete them. Once in quarantine the virus is under control and cannot harm your computer.

Rootkit

A rootkit is a form of malware designed to hide the fact that the computer system has been compromised. They can replace vital system files with malicious versions allowing hackers access to the system without being detected. They can be a single program or a combination of programs. Often they are also Trojans, masquerading as another piece of software and tricking the user into installing them.

Scareware

Scareware is a piece of software downloaded or purchased as the result of a security scam. The most common pattern is a popup or advertisement when you visit particular websites informing you that your computer is infested with viruses or that pornography has been detected. It is a form of trojan and scaring you with this sort of fake security alert prompts you to download or purchase their software (usually about $40).

The software is useless and the effects only malicious. Depending on the individual scam the only harm done may be simply parting you from your $40 (almost 2% of people who respond to these scams pay the money!!). More malicious ones may offer you a free download, which can also install adware and spyware causing further harm to your system. In all cases your computer is wide open to other attacks - there are few things worse than the false sense of security thinking you are protected by an ineffective piece of security software. The only sure way to ensure 100% protection from digital attacks is to install Internet Security or Antivirus software from one of the major companies.

Spyware

Spyware is malicious software designed to collect information about you and how you use your computer. For example, Internet browsing and shopping habits, usernames, passwords, bank and credit card details. See the Spyware page for more information.

Tracking Cookies

A Tracking Cookie is a Cookie with additional functionality. As well as 'remembering' your settings for the website that it was installed from it will also record your browsing habits - what websites you have visited, what advertisements you have seen and so on. Different websites can share the same tracking cookie and add data to it every time you visit. The main purpose is to help advertisers gather information to accurately target advertising campaigns to a relevant audience.

Tracking cookies should not be confused with Spyware, which can also gather data on usernames, passwords, account numbers and so on. Tracking cookies are only text files recording very basic information about which websites you have visited.

Trojan

A Trojan, or Trojan horse, is a malicious program that masquerades as something else - a useful piece of software, for example. It requires you to install it before infecting your computer, although you think that you are installing another program. See the Trojan page for more information.

Virus

A virus is a computer program or script that attempts to replicate itself and spread. It can spread from one computer to another, or from one file to another on the same computer. Sometimes a virus can also have a payload - a part of the program that does malicious damage such as deleting or modifying files.

Wildlist

The wildlist is a list of 'in the wild' viruses, or viruses that pose a current threat. The list has input from a number of sources and is maintained by www.wildlist.org

Worm

A worm is a network virus that spreads itself to other computers over a network. They can spread on local area networks or wide area networks such as the Internet. Most worms run automatically and need no user intervention to infect a computer, although some require user intervention of some sort - opening an email attachment, for example.