Cyber Security Glossary



Any software application that displays advertising banners while the program is running. Adware often includes code that tracks a user’s personal information and passes it on to third parties without the user’s authorization or knowledge. And if you gather enough of it, adware slows down your computer significantly. Over time, performance can be so degraded that you may have trouble working productively. See also Spyware and Malware.

Advanced persistent threat

Advanced persistent threat (APT) usually refers to a group, such as a foreign government, with both the capability and the intent to persistently and effectively target a specific entity. The term is commonly used to refer to cyber threats, in particular that of Internet-enabled espionage using a variety of intelligence gathering techniques to access sensitive information, but applies equally to other threats such as that of traditional espionage or attack. Other recognized attack vectors include infected media, supply chain compromise, and social engineering. Individuals, such as an individual hacker, are not usually referred to as an APT as they rarely have the resources to be both advanced and persistent even if they are intent on gaining access to, or attacking, a specific target.

Anti-Virus Software

Software designed to detect and potentially eliminate viruses before they have had a chance to wreak havoc within the system. Anti-virus software can also repair or quarantine files that have already been infected by virus activity. See also Virus and Electronic Infections.


Software that performs automated functions for a user, such as word processing, spreadsheets, graphics, presentations and databases—as opposed to operating system (OS) software.


A file that has been added to an email—often an image or document. It could be something useful to you or something harmful to your computer. See also Virus.


Confirming the correctness of the claimed identity of an individual user, machine, software component or any other entity.


The approval, permission or empowerment for someone or something to do something.


Hidden software or hardware mechanism used to circumvent security controls.


File copies that are saved as protection against loss, damage or unavailability of the primary data. Saving methods include high-capacity tape, separate disk sub-systems or on the Internet. Off-site backup storage is ideal, sufficiently far away to reduce the risk of environmental damage such as flood, which might destroy both the primary and the backup if kept nearby.


See Malware, Adware and Spyware.


Short for “Web log,” a blog is usually defined as an online diary or journal. It is usually updated frequently and offered in a dated log format with the most recent entry at the top of the page. It often contains links to other websites along with commentary about those sites or specific subjects, such as politics, news, pop culture or computers.


The capacity of a communication channel to pass data such as text, images, video or sound through the channel in a given amount of time. Usually expressed in bits per second.

Blacklisting Software

A form of filtering that blocks only websites specified as harmful. Parents and employers sometimes use such software to prevent children and employees from visiting certain websites. You can add and remove sites from the “not permitted” list. This method of filtering allows for more full use of the Internet, but is less efficient at preventing access to any harmful material that is not on the list. See also Whitelisting Software.

Blended Threat

A computer network attack that seeks to maximize the severity of damage and speed of contagion by combining methods—for example, using characteristics of both viruses and worms. See also Electronic Infection.


A botnet is a collection of internet-connected programs communicating with other similar programs in order to perform tasks. This can be as mundane as keeping control of an IRC channel, or it could be used to send spam email or participate in DDoS attacks. The word botnet stems from the two words robot and network.


General term used to refer to high-speed network connections such as cable modem and Digital Subscriber Line (DSL). These types of “always on” Internet connections are actually more susceptible to some security threats than computers that access the Web via dial-up service.


A client software program that can retrieve and display information from servers on the World Wide Web. Often known as a “Web browser” or “Internet browser,” Examples include Microsoft’s Internet Explorer, Google’s Chrome, Apple’s Safari, and Mozilla’s Firefox.

Brute Force Attack

An exhaustive password-cracking procedure that tries all possibilities, one by one. See also Dictionary Attack and Hybrid Attack.

Clear Desk Policy

A policy that directs all personnel to clear their desks at the end of each working day, and file everything appropriately. Desks should be cleared of all documents and papers, including the contents of the “in” and “out” trays —not simply for cleanliness, but also to ensure that sensitive papers and documents are not exposed to unauthorized persons outside of working hours.

Clear Screen Policy

A policy that directs all computer users to ensure that the contents of the screen are protected from prying eyes and opportunistic breaches of confidentially. Typically, the easiest means of compliance is to use a screen saver that engages either on request or after a specified short period of time. See also Shoulder Surfing.


A small file that is downloaded by some websites to store a packet of information on your browser. Companies and organizations use cookies to remember your login or registration identification, site preferences, pages viewed and online “shopping-cart” so that the next time you visit a site, your stored information can automatically be pulled up for you. A cookie is obviously convenient but also presents potential security issues. You can configure your browser to alert you whenever a cookie is being sent. You can refuse to accept all cookies or erase all cookies saved on your browser.


Relating to, or characteristic of, the culture of computers, information technology and virtual reality (OED)


Sending or posting harmful, cruel, rude or threatening messages, or slanderous information, text or images using the Internet or other digital communication devices.


A darknet is a private, distributed P2P file sharing network where connections are made only between trusted peers — sometimes called "friends" (F2F) — using non-standard protocols and ports.  Darknets are distinct from other distributed P2P networks as sharing is anonymous (that is, IP addresses are not publicly shared), and therefore users can communicate with little fear of governmental or corporate interference.

Denial of Service Attack

The prevention of authorized access to a system resource or the delaying of system operations and functions. Often this involves a cyber criminal generating a large volume of data requests. See also Flooding.

Dictionary Attack

A password-cracking attack that tries all of the phrases or words in a dictionary. See also Brute Force Attack and Hybrid Attack.

 Digital Certificate

The electronic equivalent of an ID card that establishes your credentials when doing business or other transactions on the Web. It contains your name, a serial number, expiration dates, a copy of the certificate holder’s public key (used for encrypting messages and digital signatures) and the digital signature of the certificate-issuing authority so that a recipient can verify that the certificate is real.

Domain Hijacking

An attack in which an attacker takes over a domain by first blocking access to the domain’s DNS server and then putting his own server up in its place.

Domain Name System (DNS)

The DNS is the way that Internet domain names are located. A website’s domain name is easier to remember than its IP (Internet Protocol) address.

Denial-of-service attack (DoS & DDoS)

In computing, a denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a machine or network resource unavailable to its intended users. Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the efforts of one or more people to temporarily or indefinitely interrupt or suspend services of a host connected to the Internet.

Perpetrators of DoS attacks typically target sites or services hosted on high-profile web servers such as banks, credit card payment gateways, and even root nameservers. This technique has now seen extensive use in certain games, used by server owners, or disgruntled competitors on games such as Minecraft and League of Legends. The term is generally used relating to computer networks, but is not limited to this field; for example, it is also used in reference to CPU resource management.

One common method of attack involves saturating the target machine with external communications requests, so much so that it cannot respond to legitimate traffic, or responds so slowly as to be rendered essentially unavailable. Such attacks usually lead to a server overload. In general terms, DoS attacks are implemented by either forcing the targeted computer(s) to reset, or consuming its resources so that it can no longer provide its intended service or obstructing the communication media between the intended users and the victim so that they can no longer communicate adequately.

Denial-of-service attacks are considered violations of the IAB's Internet proper use policy, and also violate the acceptable use policies of virtually all Internet service providers. They also commonly constitute violations of the laws of individual nations.

Dumpster Diving

Recovering files, letters, memos, photographs, IDs, passwords, checks, account statements, credit card offers and more from garbage cans and recycling bins. This information can then be used to commit identity theft.

Electronic Infections

Often called “viruses,” these malicious programs and codes harm your computer and compromise your privacy. In addition to the traditional viruses, other common types include worms and Trojan horses. They sometimes work in tandem to do maximum damage. See also Blended Threat.


A data security technique used to protect information from unauthorized inspection or alteration. Information is encoded so that it appears as a meaningless string of letters and symbols during delivery or transmission. Upon receipt, the information is decoded using an encryption key.

End User License Agreement (EULA)

A contract between you and your software’s vendor or developer. Many times, the EULA is presented as a dialog box that appears the first time you open the software and forces you to check “I accept” before you can proceed. Before accepting, though, read through it and make sure you understand and are comfortable with the terms of the agreement. If the software’s EULA is hard to understand or you can’t find it, beware!

Evil Twins

A fake wireless Internet hot spot that looks like a legitimate service. When victims connect to the wireless network, a hacker can launch a spying attack on their transactions on the Internet, or just ask for credit card information in the standard pay-for-access deal. See also Man-in-the-Middle Attacks.

File-Sharing Programs

Sometimes called peer-to-peer (P2P) programs, these allow many different users to access the same file at the same time. These programs are often used to illegally upload and download music and other software. Examples include Napster, Grokster, Kazaa, iMesh, Ares and Limewire.


A hardware or software link in a network that inspects all data packets coming and going from a computer, permitting only those that are authorized to reach the other side.


An attack that attempts to cause a failure in the security of a computer by providing more input, such as a large volume of data requests, than it can properly process. See also Denial of Service Attack.

Forensic Discovery 

Forensic or E-discovery is the search and analysis of electronic documents and data. Electronic documents include virtually anything that is stored on a computer such as e-mail, web pages, word processing files, and computer databases. Electronic records can be found on a wide variety of devices such as desktop and laptop computers, network servers, personal digital assistants and digital phones. Documents and data are "electronic" if they exist in a medium that can only be read by using computers such as cache memory, magnetic disks (for example computer hard drives or floppy disks), optical disks (for example DVDs or CDs), and magnetic tapes. Electronic discovery is frequently distinguished from traditional "paper discovery," which is the discovery of writings on paper that can be read without the assistance of computers. Forensic Discovery is frequently required in legal proceedings and is submitted as evidence in Court.


Using the Internet to manipulate and gain trust of a minor as a first step towards the future sexual abuse, production or exposure of that minor. Sometimes involves developing the child’s sexual awareness and may take days, weeks, months or in some cases years to manipulate the minor.


An individual who attempts to break into a computer without authorization.


A honeypot is a trap set to detect, deflect, or in some manner counteract attempts at unauthorized use of information systems. Generally it consists of a computer, data, or a network site that appears to be part of a network, but is actually isolated and monitored, and which seems to contain information or a resource of value to attackers.


When used in the first part of a URL (e.g., http://), this term specifies the use of hypertext transfer protocol (HTTP) enhanced by a security mechanism such as Secure Socket Layer (SSL). Always look for the HTTPS on the checkout or order form page when shopping online or when logging into a site and providing your username and password.

Hybrid Attack

Builds on other password-cracking attacks by adding numerals and symbols to dictionary words. See also Dictionary Attack and Brute Force Attack.


An incident is an event attributable to a human root cause. This distinction is particularly important when the event is the product of malicious intent to do harm. An important note: all incidents are events but many events are not incidents. A system or application failure due to age or defect may be an emergency event but a random flaw or failure is not an incident.

Incident response team

The incident coordinator manages the response process and is responsible for assembling the team. The coordinator will ensure the team includes all the individuals necessary to properly assess the incident and make decisions regarding the proper course of action. The incident team meets regularly to review status reports and to authorize specific remedies. The team should utilize a pre-allocated physical and virtual meeting place.

Incident investigation

The investigation seeks to determine the circumstances of the incident. Every incident will warrant or require an investigation. However, investigation resources like forensic tools, dirty networks, quarantine networks and consultation with law enforcement may be useful for the effective and rapid resolution of an emergency incident.

Instant Messaging (IM)

A service that allows people to send and get messages almost instantly. To send messages using instant messaging you need to download an instant messaging program and know the instant messaging address of another person who uses the same IM program. See also Spim.

IP (Internet Protocol) Address

A computer’s inter-network address, written as a series of four 8-bit numbers separated by periods, such as 123.45.678.990. Every website has an IP Address, although finding a website is considerably easier to do when using its domain name instead. See also Domain Name System (DNS).

Internet Service Provider (ISP)

A company that provides internet access to customers.

Keystroke Logger

A specific type of electronic infection that records victims’ keystrokes and sends them to an attacker. This can be done with either hardware or software. See also Trojan Horse.


A generic term for a number of different types of malicious code. See also Adware and Spyware.

Man-In-the-Middle Attack

Posing as an online bank or merchant, a cyber criminal allows a victim to sign in over a Secure Sockets Layer (SSL) connection. The attacker then logs onto the real server using the client’s information and steals credit card numbers.

Monitoring Software

Software products that allow parents to monitor or track the websites or email messages that a child visits or reads. See also Blacklisting Software and Whitelisting Software.


Two or more computer systems that are grouped together to share information, software and hardware.

Operating System (OS)

Programs that manage all the basic functions and programs on a computer, such as allocating system resources, providing access and security controls, maintaining file systems and managing communications between end users and hardware devices. Examples include Microsoft’s Windows, Apple’s Macintosh and Red Hat’s Linux.


A secret sequence of characters that is used as a means of authentication to confirm your identity in a computer program or online.

Password Cracking

Password cracking is the process of attempting to guess passwords, given the password file information. See also Brute Force Attacks, Dictionary Attacks and Hybrid Attacks.

Password Sniffing

Passive wiretapping, usually on a local area network, to gain knowledge of passwords.


A patch is a small security update released by a software manufacturer to fix bugs in existing programs. Your computer’s software programs and/or operating system may be configured to check automatically for patches, or you may need to periodically visit the manufacturers’ websites to see if there have been any updates.

Peer-to-Peer (P2P) Programs

See File-Sharing Programs.

Penetration Test

A penetration test, occasionally pentest, is a method of evaluating the computer security of a computer system or network by simulating an attack from malicious outsiders (who do not have an authorized means of accessing the organization's systems) and malicious insiders (who have some level of authorized access). The process involves an active analysis of the system for any potential vulnerabilities that could result from poor or improper system configuration, both known and unknown hardware or software flaws, or operational weaknesses in process or technical countermeasures. This analysis is carried out from the position of a potential attacker and can involve active exploitation of security vulnerabilities.

Effective penetration tests provides an accurate assessment of the potential impacts to the organization and outline a range of technical and procedural countermeasures to reduce risks.


Soliciting private information from customers or members of a business, bank or other organization in an attempt to fool them into divulging confidential personal and financial information. People are lured into sharing user names, passwords, account information or credit card numbers, usually by an official-looking message in an email or a pop-up advertisement that urges them to act immediately, usually by clicking on a link provided. See also Vishing.


Redirecting visitors from a real website to a bogus one. A user enters what is believed to be a valid Web address and is unknowingly redirected to an illegitimate site that steals the user's personal information. On the spoofed site, criminals may mimic real transactions and harvest private information unknowingly shared by users. With this, the attacker can then access the real website and conduct transactions using the credentials of a valid user.


A hardware device that connects two or more networks and routes incoming data packets to the appropriate network. Many Internet Service Providers (ISPs) provide these devices to their customers, and they often contain firewall protections.


A file containing active content -- for example, commands or instructions to be executed by the computer.

Shoulder Surfing

Looking over a person’s shoulder to get confidential information. It is an effective way to get information in crowded places because it’s relatively easy to stand next to someone and watch as they fill out a form, enter a PIN number at an ATM machine or type a password. Can also be done long-distance with the aid of binoculars or other vision- enhancing devices. To combat it, experts recommend that you shield paperwork or your keypad from view by using your body or cupping your hand. Also, be sure you password- protect your computer screen when you must leave it unattended, and clear your desk at the end of the day. See also Clear Desk Policy and Clear Screen Policy.


A high-tech method by which thieves capture your personal or account information from your credit card, driver’s license or even passport using an electronic device called a “skimmer.” Such devices can be purchased online for under $50. Your card is swiped through the skimmer and the information contained in the magnetic strip on the card is then read into and stored on the device or an attached computer. Skimming is predominantly a tactic used to perpetuate credit card fraud, but is also gaining in popularity amongst identity thieves.

Social Engineering

A euphemism for non-technical or low-technology means—such as lies, impersonation, tricks, bribes, blackmail and threats—used to attack information systems. Sometimes telemarketers or unethical employees employ such tactics.

Social Networking Websites

Sites specifically focused on the building and verifying of social networks for whatever purpose. Many social networking services are also blog hosting services. There are more than 300 known social networking websites, including Facebook, Twitter, LinkedIn, MySpace and Blogspot. Such sites enable users to create online profiles and post pictures and share personal data such as their contact information, hobbies, activities and interests. The sites facilitate connecting with other users with similar interests, activities and locations. Sites vary in who may view a user’s profile—some have settings which may be changed so that profiles can be viewed only by “friends.” See also Blogs.


Unwanted, unsolicited email from someone you don’t know. Often sent in an attempt to sell you something or get you to reveal personal information.


Unwanted, unsolicited instant messages from someone you don’t know. Often sent in an attempt to sell you something or get you to reveal personal information.


Masquerading so that a trusted IP address is used instead of the true IP address. A technique used by hackers as a means of gaining access to a computer system.


Software that uses your Internet connection to send personally identifiable information about you to a collecting device on the Internet. It is often packaged with software that you download voluntarily, so that even if you remove the downloaded program later, the spyware may remain. See also Adware and Malware.

SSL (Secure Socket Layer)

An encryption system that protects the privacy of data exchanged by a website and the individual user. Used by websites whose URLs begin with https instead of http.

Trojan Horse

A computer program that appears to be beneficial or innocuous, but also has a hidden and potentially malicious function that evades security mechanisms. A “keystroke logger,” which records victims’ keystrokes and sends them to an attacker, or remote-controlled “zombie computers” are examples of the damage that can be done by Trojan horses. See also Electronic Infection.


Abbreviation for “Uniform (or Universal) Resource Locator.” A way of specifying the location of publicly available information on the Internet. Also known as a Web address.

URL Obfuscation

Taking advantage of human error, some scammers use phishing emails to guide recipients to fraudulent sites with names very similar to established sites. They use a slight misspelling or other subtle difference in the URL, such as “” instead of “” to redirect users to share their personal information unknowingly.


A hidden, self-replicating section of computer software, usually malicious logic, that propagates by infecting—i.e., inserting a copy of itself into and becoming part of -- another program. A virus cannot run by itself; it requires that its host program be run to make the virus active. Often sent through email attachments. Also see Electronic Infection and Blended Threat.


Soliciting private information from customers or members of a business, bank or other organization in an attempt to fool them into divulging confidential personal and financial information. People are lured into sharing user names, passwords, account information or credit card numbers, usually by an official-looking message in an email or a pop-up advertisement that urges them to act immediately—but in a vishing scam, they are urged to call the phone number provided rather than clicking on a link. See also Phishing.


A flaw that allows someone to operate a computer system with authorization levels in excess of that which the system owner specifically granted.


Vulnerability Assessment

A vulnerability assessment is the process of identifying, quantifying, and prioritizing (or ranking) the vulnerabilities in a system. Examples of systems for which vulnerability assessments are performed include, but are not limited to, information technology systems, energy supply systems, water supply systems, transportation systems, and communication systems. Such assessments may be conducted on behalf of a range of different organizations, from small businesses up to large regional infrastructures. 

A Vulnerability Assessment has many things in common with risk assessment  and provides information on the flaws within the system that can be exploited along with recommendations on measures and processes to adopt or alter.

Whitelisting Software

A form of filtering that only allows connections to a pre-approved list of sites that are considered useful and appropriate for children. Parents sometimes use such software to prevent children from visiting all but certain websites. You can add and remove sites from the “permitted” list. This method is extremely safe, but allows for only extremely limited use of the Internet.


Originally an acronym for “Write once, read many times,” a type of electronic infection that can run independently, can propagate a complete working version of itself onto other hosts on a network, and may consume computer resources destructively. Once this malicious software is on a computer, it scans the network for another machine with a specific security vulnerability. When it finds one, it exploits the weakness to copy itself to the new machine, and then the worm starts replicating from there, as well. See also Electronic Infection and Blended Threat.

Zombie Computer

A remote-access Trojan horse installs hidden code that allows your computer to be controlled remotely. Digital thieves then use robot networks of thousands of zombie computers to carry out attacks on other people and cover up their tracks. Authorities have a harder time tracing criminals when they go through zombie computers.