Cybersecurity Glossary

Cybersecurity glossary which contains key cybersecurity terms that enable clear communication and a common understanding of cybersecurity definitions.

Glossary of Common Cybersecurity Terminology

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Definition: The ability and means to communicate with or otherwise interact with a system, to use system resources to handle information, to gain knowledge of the information the system contains, or to control system components and functions.

access and identity management
Synonym(s): identity and access management

access control
Definition: The process of granting or denying specific requests for or attempts to:

  1. obtain and use information and related information processing services
  2. enter specific physical facilities.
Related Term(s): access control mechanism

access control mechanism
Definition: Security measures designed to detect and deny unauthorized access and permit authorized access to an information system or a physical facility.

active attack
Definition: An actual assault perpetrated by an intentional threat source that attempts to alter a system, its resources, its data, or its operations.

Related Term(s): passive attack

active content
Definition: Software that is able to automatically carry out or trigger actions without the explicit intervention of a user.

Advanced Persistent Threat
Definition: An adversary that possesses sophisticated levels of expertise and significant resources which allow it to create opportunities to achieve its objectives by using multiple attack vectors (e.g., cyber, physical, and deception).

Definition: An individual, group, organization, or government that conducts or has the intent to conduct detrimental activities.

Related Term(s): threat agent, attacker

air gap
Definition: To physically separate or isolate a system from other systems or networks (verb).

Extended Definition: The physical separation or isolation of a system from other systems or networks (noun).

Definition: A notification that a specific attack has been detected or directed at an organization’s information systems.

All Source Intelligence
Definition: A cybersecurity service that analyzes threat information from multiple sources, disciplines, and agencies across the Intelligence Community. Synthesizes and places intelligence information in context; draws insights about the possible implications.

Definition: A Cybersecurity service responsible for highly specialized review and evaluation of incoming cybersecurity information to determine its usefulness for intelligence.

antispyware software
Definition: A program that specializes in detecting and blocking or removing forms of spyware.

Related Term(s): spyware

antivirus software
Definition: A program that monitors a computer or network to detect or identify major types of malicious code and to prevent or contain malware incidents. Sometimes by removing or neutralizing the malicious code.

Definition: A person, structure, facility, information, and records, information technology systems and resources, material, process, relationships, or reputation that has value.

Extended Definition: Anything useful that contributes to the success of something, such as an organizational mission; assets are things of value or properties to which value can be assigned.

asymmetric cryptography
Synonym(s): public key cryptography

Definition: An attempt to gain unauthorized access to system services, resources, or information, or an attempt to compromise system integrity.

Extended Definition: The intentional act of attempting to bypass one or more security services or controls of an information system.

Related Term(s): active attack, passive attack

attack method
Definition: The manner or technique and means an adversary may use in an assault on information or an information system.

attack mode

Synonym(s): attack method

attack path
Definition: The steps that an adversary takes or may take to plan, prepare for, and execute an attack.

attack pattern
Definition: Similar cyber events or behaviors that may indicate an attack has occurred or is occurring, resulting in a security violation or a potential security violation.

Extended Definition: For software, descriptions of common methods for exploiting software systems.

Related Term(s): attack signature

attack signature
Definition: A characteristic or distinctive pattern that can be searched for or that can be used in matching to previously identified attacks.

Extended Definition: An automated set of rules for identifying a potential threat (such as an exploit or the presence of an attacker tool) and possible responses to that threat.

Related Term(s): attack pattern

attack surface
Definition: The set of ways in which an adversary can enter a system and potentially cause damage.

Extended Definition: An information system's characteristics that permit an adversary to probe, attack, or maintain presence in the information system.

Definition: An individual, group, organization, or government that executes an attack.

Extended Definition: A party acting with malicious intent to compromise an information system.

Related Term(s): adversary, threat agent


Related Term(s): authentication

Definition: The process of verifying the identity or other attributes of an entity (user, process, or device).

Extended Definition: Also the process of verifying the source and integrity of data.

Definition: A property achieved through cryptographic methods of being genuine and being able to be verified and trusted, resulting in confidence in the validity of a transmission, information or a message, or sender of information or a message.

Related Term(s): integrity, non-repudiation

Definition: A process of determining, by evaluating applicable access control information, whether a subject is allowed to have the specified types of access to a particular resource.

Extended Definition: The process or act of granting access privileges or the access privileges as granted.

Definition: The property of being accessible and usable upon demand.

Extended Definition: In cybersecurity, applies to assets such as information or information systems.

Related Term(s): confidentiality, integrity


behavior monitoring
Definition: Observing activities of users, information systems, and processes and measuring the activities against organizational policies and rule, baselines of normal activity, thresholds, and trends.

behavioral monitoring

Definition: A list of entities that are blocked or denied privileges or access.

Related Term(s): whitelist

Blue Team
Definition: A group that defends an enterprise's information systems when mock attackers (i.e., the Red Team) attack, typically as part of an operational exercise conducted according to rules established and monitored by a neutral group (i.e., the White Team).

Extended Definition: Also, a group that conducts operational vulnerability evaluations and recommends mitigation techniques to customers who need an independent technical review of their cybersecurity posture.

Related Term(s): Red Team, White Team

Definition: A computer connected to the Internet that has been surreptitiously / secretly compromised with malicious logic to perform activities under remote the command and control of a remote administrator.

Extended Definition: A member of a larger collection of compromised computers known as a botnet.

Synonym(s): zombie

Related Term(s): botnet

bot herder

Synonym(s): bot master

bot master
Definition: The controller of a botnet that, from a remote location, provides direction to the compromised computers in the botnet.

Synonym(s): bot herder

Definition: A collection of computers compromised by malicious code and controlled across a network.

Definition: An unexpected and relatively small defect, fault, flaw, or imperfection in an information system or device.

Build Security In
Definition: A set of principles, practices, and tools to design, develop, and evolve information systems and software that enhance resistance to vulnerabilities, flaws, and attacks.


Definition: The means to accomplish a mission, function, or objective.

Related Term(s): intent


Synonym(s): cryptographic algorithm

Definition: Data or information in its encrypted form.

Related Term(s): plaintext

cloud computing
Definition: A model for enabling on-demand network access to a shared pool of configurable computing capabilities or resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.

Collect & Operate
Definition: Cybersecurity service category consisting of specialty areas responsible for specialized denial and deception operations and collection of cybersecurity information that may be used to develop intelligence.

Collection Operations
Definition: Cybersecurity service that executes collection using appropriate strategies and within the priorities established through the collection management process.

computer forensics

Synonym(s): digital forensics

computer network defense
Definition: The actions taken to defend against unauthorized activity within computer networks.

Computer Network Defense Analysis
Definition: Cybersecurity service that uses defensive measures and information collected from a variety of sources to identify, analyze, and report events that occur or might occur within the network in order to protect information, information systems, and networks from threats.

Computer Network Defense Infrastructure Support
Definition: Cybersecurity service that tests, implements, deploys, maintains, reviews, and administers the infrastructure hardware and software that are required to effectively manage the computer network defense service provider network and resources; monitors network to actively remediate unauthorized activities.

computer security incident

Synonym(s): incident

Related Term(s): event

Definition: A property that information is not disclosed to users, processes, or devices unless they have been authorized to access the information.

Extended Definition: Preserving authorized restrictions on information access and disclosure, including means for protecting personal privacy and proprietary information.

Related Term(s): availability, integrity

Definition: The effect of an event, incident, or occurrence.

Extended Definition: In cybersecurity, the effect of a loss of confidentiality, integrity or availability of information or an information system on an organization's operations, its assets, on individuals, other organizations, or on national interests.

Continuity of Operations Plan
Definition: A document that sets forth procedures for the continued performance of core capabilities and critical operations during any disruption or potential disruption.

Related Term(s): Business Continuity Plan, Disaster Recovery Plan, Contingency Plan

critical infrastructure

Definition: The systems and assets, whether physical or virtual, so vital to society that the incapacity or destruction of such may have a debilitating impact on the security, economy, public health or safety, environment, or any combination of these matters.

Related Term(s): key resource

critical infrastructure and key resources

Synonym(s): critical infrastructure

Definition: The operations performed in defeating or circumventing cryptographic protection of information by applying mathematical techniques and without an initial knowledge of the key employed in providing the protection.

Extended Definition: The study of mathematical techniques for attempting to defeat or circumvent cryptographic techniques and/or information systems security.

cryptographic algorithm
Definition: A well-defined computational procedure that takes variable inputs, including a cryptographic key, and produces an output.

Related Term(s): key, encryption, decryption, symmetric key, asymmetric key

Definition: The use of mathematical techniques to provide security services, such as confidentiality, data integrity, entity authentication, and data origin authentication.

Extended Definition: The art or science concerning the principles, means, and methods for converting plaintext into ciphertext and for restoring encrypted ciphertext to plaintext.

Related Term(s): plaintext, ciphertext, encryption, decryption

Definition: The mathematical science that deals with cryptanalysis and cryptography.

Related Term(s): cryptanalysis, cryptography

Customer Service and Technical Support
Definition: Cybersecurity service that addresses problems, installs, configures, troubleshoots, and provides maintenance and training in response to customer requirements or inquiries (e.g., tiered-level customer support).

cyber ecosystem
Definition: The interconnected information infrastructure of interactions among persons, processes, data, and information and communications technologies, along with the environment and conditions that influence those interactions.

cyber exercise
Definition: A planned event during which an organization simulates a cyber disruption to develop or test capabilities such as preventing, detecting, mitigating, responding to or recovering from the disruption.

cyber incident

Synonym(s): incident

Related Term(s): event

cyber incident response plan

Synonym(s): incident response plan

cyber infrastructure
Definition: An electronic information and communications systems and services and the information contained therein.

Extended Definition: The information and communications systems and services composed of all hardware and software that process, store, and communicate information, or any combination of all of these elements:

  • Processing includes the creation, access, modification, and destruction of information.
  • Storage includes paper, magnetic, electronic, and all other media types.
  • Communications include sharing and distribution of information.

Cyber Operations
Definition: Cybersecurity service that performs activities to gather evidence on criminal or foreign intelligence entities in order to mitigate possible or real-time threats, protect against espionage or insider threats, foreign sabotage, international terrorist activities, or to support other intelligence activities.

From: NICE Workforce Framework

Cyber Operations Planning
Definition: Cybersecurity service that performs in-depth joint targeting and cyber planning process. Gathers information and develops detailed Operational Plans and Orders supporting requirements. Conducts strategic and operational-level planning across the full range of operations for integrated information and cyberspace operations

Definition: The activity or process, ability or capability, or state whereby information and communications systems and the information contained therein are protected from and/or defended against damage, unauthorized use or modification, or exploitation.

Extended Definition: Strategy, policy, and standards regarding the security of and operations in cyberspace, and encompass[ing] the full range of threat reduction, vulnerability reduction, deterrence, international engagement, incident response, resiliency, and recovery policies and activities, including computer network operations, information assurance, law enforcement, diplomacy, military, and intelligence missions as they relate to the security and stability of the global information and communications infrastructure.

Definition: The interdependent network of information technology infrastructures, that includes the Internet, telecommunications networks, computer systems, and embedded processors and controllers.


Data Administration
Definition: Cybersecurity service that develops and administers databases and/or data management systems that allow for the storage, query, and utilization of data.

data aggregation
Definition: The process of gathering and combining data from different sources, so that the combined data reveals new information.

Extended Definition: The new information is more sensitive than the individual data elements themselves and the person who aggregates the data was not granted access to the totality of the information.

Related Term(s): data mining

data breach
Definition: The unauthorized movement or disclosure of sensitive information to a party, usually outside the organization, that is not authorized to have or see the information.

Related Term(s): data loss, data theft, exfiltration

data integrity
Definition: The property that data is complete, intact, and trusted and has not been modified or destroyed in an unauthorized or accidental manner.

Related Term(s): integrity, system integrity

data leakage
Synonym(s): data breach

data loss
Definition: The result of unintentionally or accidentally deleting data, forgetting where it is stored, or exposure to an unauthorized party.

Related Term(s): data leakage, data theft

data loss prevention

Definition: A set of procedures and mechanisms to stop sensitive data from leaving a security boundary.

Related Term(s): data loss, data theft, data leak

data mining
Definition: The process or techniques used to analyze large sets of existing information to discover previously unrevealed patterns or correlations.

Related Term(s): data aggregation

data spill

Synonym(s): data breach

data theft
Definition: The deliberate or intentional act of stealing of information.

Related Term(s): data aggregation, data leakage, data loss

Definition: To convert enciphered text to plain text by means of a cryptographic system.

Synonym(s): decode, decrypt

Definition: To convert encoded text to plain text by means of a code.

Synonym(s): decipher, decrypt

Definition: A generic term encompassing decode and decipher.

Synonym(s): decipher, decode

Definition: The process of transforming ciphertext into its original plaintext.
Extended Definition: The process of converting encrypted data back into its original form, so it can be understood.

Synonym(s): decode, decrypt, decipher

denial of service (DOS)
Definition: An attack that prevents or impairs the authorized use of information system resources or services.

designed-in security

Synonym(s): Build Security In

digital forensics
Definition: The processes and specialized techniques for gathering, retaining, and analyzing system-related data (digital evidence) for investigative purposes.

Extended Definition: Cybersecurity service that collects, processes, preserves, analyzes, and presents computer-related evidence in support of network vulnerability, mitigation, and/or criminal, fraud, counterintelligence or law enforcement investigations.

Synonym(s): computer forensics, forensics

digital rights management
Definition: A form of access control technology to protect and manage use of digital content or devices in accordance with the content or device provider's intentions.

digital signature
Definition: A value computed with a cryptographic process using a private key and then appended to a data object, thereby digitally signing the data.
Related Term(s): electronic signature

Definition: An event which causes unplanned interruption in operations or functions for an unacceptable length of time.

distributed denial of service (DDOS)
Definition: A denial of service technique that uses numerous systems to perform the attack simultaneously. Botnets are used to carry out these attacks by sending massive volumes of requests that consume bandwidth.

Related Term(s): denial of service, botnet

dynamic attack surface
Definition: The automated, on-the-fly changes of an information system's characteristics to thwart actions of an adversary.

DNS Attack
Definition: DNS stands for domain name server or domain name system. DNS translates website addresses (such as into IP addresses (a location on the internet). A DNS attack hijacks a legitimate website’s IP address and points it to a malicious site controlled by the attacker.


Education and Training

Definition: Cybersecurity service that conducts training of personnel within pertinent subject domain; develop, plan, coordinate, deliver, and/or evaluate training courses, methods, and techniques as appropriate.

electronic signature
Definition: Any mark in electronic form associated with an electronic document, applied with the intent to sign the document.

Related Term(s): digital signature

Definition: To convert plaintext to ciphertext by means of a cryptographic system.

Synonym(s): encode, encrypt

Definition: To convert plaintext to ciphertext by means of a code.

Synonym(s): encipher, encrypt

Definition: The generic term encompassing encipher and encode.

Synonym(s): encipher, encode

Definition: The process of transforming plaintext into ciphertext.

Extended Definition: Converting data into a form that cannot be easily understood by unauthorized people.

Synonym(s): encode, encrypt, encipher

enterprise risk management
Definition: A comprehensive approach to risk management that engages people, processes, and systems across an organization to improve the quality of decision making for managing risks that may hinder an organization’s ability to achieve its objectives.

Extended Definition: Involves identifying mission dependencies on enterprise capabilities, identifying and prioritizing risks due to defined threats, implementing countermeasures to provide both a static risk posture and an effective dynamic response to active threats; and assessing enterprise performance against threats and adjusts countermeasures as necessary.

Related Term(s): risk management, integrated risk management, risk

Definition: An observable occurrence in an information system or network.

Extended Definition: Sometimes provides an indication that an incident is occurring or at least raise the suspicion that an incident may be occurring.

Related Term(s): incident

Definition: The unauthorized transfer of information from an information system.

Related Term(s): data breach

Definition: A technique to breach the security of a network or information system in violation of security policy.

Exploitation Analysis
Definition: Cybersecurity service that analyzes collected information to identify vulnerabilities and potential for exploitation.

Definition: The condition of being unprotected, thereby allowing access to information or access to capabilities that an attacker can use to enter a system or network.



Definition: The inability of a system or component to perform its required functions within specified performance requirements.


Definition: A capability to limit network traffic between networks and/or information systems.

Extended Definition: A hardware/software device or a software program that limits network traffic according to a set of rules of what access is and is not allowed or authorized.


Synonym(s): digital forensics




Definition: An unauthorized user who attempts to or gains access to an information system.

hash value
Definition: A numeric value resulting from applying a mathematical algorithm against a set of data such as a file.

Synonym(s): cryptographic hash value

Related Term(s): hashing

Definition: A process of applying a mathematical algorithm against a set of data to produce a numeric value (a 'hash value') that represents the data.

Extended Definition: Mapping a bit string of arbitrary length to a fixed length bit string to produce the hash value.

Related Term(s): hash value

Definition: A natural or man-made source or cause of harm or difficulty.

Related Term(s): threat


ICT supply chain threat

Definition: A man-made threat achieved through exploitation of the information and communications technology (ICT) system’s supply chain, including acquisition processes.

Related Term(s): supply chain, threat

identity and access management
Definition: The methods and processes used to manage subjects and their authentication and authorizations to access specific objects.

Synonym(s): consequence

Definition: An occurrence that actually or potentially results in adverse consequences to (adverse effects on) (poses a threat to) an information system or the information that the system processes, stores, or transmits and that may require a response action to mitigate the consequences.

Extended Definition: An occurrence that constitutes a violation or imminent threat of violation of security policies, security procedures, or acceptable use policies.

Related Term(s): event

incident management
Definition: The management and coordination of activities associated with an actual or potential occurrence of an event that may result in adverse consequences to information or information systems.

incident response
Definition: The activities that address the short-term, direct effects of an incident and may also support short-term recovery.

Extended Definition: Cybersecurity service that responds to crisis or urgent situations within the pertinent domain to mitigate immediate and potential threats; uses mitigation, preparedness, and response and recovery approaches, as needed, to maximize survival of life, preservation of property, and information security. Investigates and analyzes all relevant response activities.

Synonym(s): response

Related Term(s): recovery

incident response plan
Definition: A set of predetermined and documented procedures to detect and respond to a cyber incident.

Definition: An occurrence or sign that an incident may have occurred or may be in progress.

Related Term(s): precursor

Industrial Control System
Definition: An information system used to control industrial processes such as manufacturing, product handling, production, and distribution or to control infrastructure assets.

Related Term(s): Supervisory Control and Data Acquisition, Operations Technology

information and communication(s) technology
Definition: Any information technology, equipment, or interconnected system or subsystem of equipment that processes, transmits, receives, or interchanges data or information.

Related Term(s): information technology

information assurance

Definition: The measures that protect and defend information and information systems by ensuring their availability, integrity, and confidentiality.

Related Term(s): information security

Information Assurance Compliance
Definition: cybersecurity service that oversees, evaluates, and supports the documentation, validation, and accreditation processes necessary to assure that new IT systems meet the organization's information assurance and security requirements; ensures appropriate treatment of risk, compliance, and assurance from internal and external perspectives.

information security policy
Definition: An aggregate of directives, regulations, rules, and practices that prescribe how an organization manages, protects, and distributes information.

Related Term(s): security policy

information sharing
Definition: An exchange of data, information, and/or knowledge to manage risks or respond to incidents.

information system resilience
Definition: The ability of an information system to: (1) continue to operate under adverse conditions or stress, even if in a degraded or debilitated state, while maintaining essential operational capabilities; and (2) recover effectively in a timely manner.

Related Term(s): resilience

Information Systems Security Operations
Definition: A cybersecurity service that oversees the information assurance program of an information system in or outside the network environment; may include procurement duties (e.g., Information Systems Security Officer).

information technology
Definition: Any equipment or interconnected system or subsystem of equipment that processes, transmits, receives, or interchanges data or information.

Related Term(s): information and communication(s) technology

inside(r) threat
Definition: A person or group of persons within an organization who pose a potential risk through violating security policies.

Extended Definition: One or more individuals with the access and/or inside knowledge of a company, organization, or enterprise that would allow them to exploit the vulnerabilities of that entity's security, systems, services, products, or facilities with the intent to cause harm.

Related Term(s): outside(r) threat

integrated risk management
Definition: The structured approach that enables an enterprise or organization to share risk information and risk analysis and to synchronize independent yet complementary risk management strategies to unify efforts across the enterprise.

Related Term(s): risk management, enterprise risk management

Definition: The property whereby information, an information system, or a component of a system has not been modified or destroyed in an unauthorized manner.

Extended Definition: A state in which information has remained unaltered from the point it was produced by a source, during transmission, storage, and eventual receipt by the destination.

Related Term(s): availability, confidentiality, data integrity, system integrity

Definition: A state of mind or desire to achieve an objective.

Related Term(s): capability

Definition: The ability of two or more systems or components to exchange information and to use the information that has been exchanged.
Adapted from: IEEE Standard Computer Dictionary, DHS personnel

Definition: An unauthorized act of bypassing the security mechanisms of a network or information system.

Synonym(s): penetration

intrusion detection
Definition: The process and methods for analyzing information from networks and information systems to determine if a security breach or security violation has occurred.

Definition: A Workforce Framework category consisting of specialty areas responsible for the investigation of cyber events and/or crimes of IT systems, networks, and digital evidence

Definition: A systematic and formal inquiry into a qualified threat or incident using digital forensics and perhaps other traditional criminal inquiry techniques to determine the events that transpired and to collect evidence.

Extended Definition: Cybersecurity service tha applies tactics, techniques, and procedures for a full range of investigative tools and processes to include but not limited to interview and interrogation techniques, surveillance, counter surveillance, and surveillance detection, and appropriately balances the benefits of prosecution versus intelligence gathering.

IT asset

Synonym(s): asset


Definition : Emitting electromagnetic energy on a wireless network’s frequencies to make them unusable by the network.

A deliberate communications disruption meant to degrade the operational performance of the RF subsystem. Jamming is achieved by interjecting electromagnetic waves on the same frequency that the reader to tag uses for communication.


Kernel mode
Definition: Used for execution of privileged instructions for the internal operation of the system. In kernel mode, there are no protections from errors or malicious activity and all parts of the system and memory are accessible.

Definition: The numerical value used to control cryptographic operations, such as decryption, encryption, signature generation, or signature verification.
Related Term(s): private key, public key, secret key, symmetric key

key pair
Definition: A public key and its corresponding private key.

Extended Definition: Two mathematically related keys having the property that one key can be used to encrypt a message that can only be decrypted using the other key.

Related Term(s): private key, public key

key resource
Definition: A publicly or privately controlled asset necessary to sustain continuity of government and/or economic operations, or an asset that is of great historical significance.

Related Term(s): critical infrastructure

Definition: Software or hardware that tracks keystrokes and keyboard events, usually surreptitiously / secretly, to monitor actions by the user of an information system.

Related Term(s): spyware

Knowledge Management
Definition: A cybersecurity service that manages and administers processes and tools that enable the organization to identify, document, and access intellectual capital and information content.


Definition: To record details of information or events in an organized record-keeping system, usually sequenced in the order in which they occurred.

Logical access
Definition: Ability to interact with computer resources granted using identification, authentication and authorization.

Logical access controls
Definition: The policies, procedures, organizational structure and electronic access controls designed to restrict access to computer software and data files.


machine learning and evolution

Definition: A field concerned with designing and developing artificial intelligence algorithms for automated knowledge discovery and innovation by information systems.

macro virus
Definition: A type of malicious code that attaches itself to documents and uses the macro programming capabilities of the document’s application to execute, replicate, and spread or propagate itself.

Related Term(s): virus

malicious applet
Definition: A small application program that is automatically downloaded and executed and that performs an unauthorized function on an information system.

Related Term(s): malicious code

malicious code
Definition: Program code intended to perform an unauthorized function or process that will have adverse impact on the confidentiality, integrity, or availability of an information system.

Extended Definition: Includes software, firmware, and scripts.

Related Term(s): malicious logic

malicious logic
Definition: Hardware, firmware, or software that is intentionally included or inserted in a system to perform an unauthorized function or process that will have adverse impact on the confidentiality, integrity, or availability of an information system.

Related Term(s): malicious code

Definition: Software that compromises the operation of a system by performing an unauthorized function or process.
Synonym(s): malicious code, malicious applet, malicious logic

Mandatory access control (MAC)
Definition: A means of restricting access to data based on varying degrees of security requirements for information contained in the objects and the corresponding security clearance of users or programs acting on their behalf.

Man-in-the-middle attack
An attack strategy in which the attacker intercepts the communication stream between two parts of the victim system and then replaces the traffic between the two components with the intruder’s own, eventually assuming control of the communication.

Miniature fragment attack
Definition: Using this method, an attacker fragments the IP packet into smaller ones and pushes it through the firewall, in the hope that only the first of the sequence of fragmented packets would be examined and the others would pass without review.

Definition: The application of one or more measures to reduce the likelihood of an unwanted occurrence and/or lessen its consequences.

Extended Definition: Implementing appropriate risk-reduction controls based on risk management priorities and analysis of alternatives.

moving target defense
Definition: The presentation of a dynamic attack surface, increasing an adversary's work factor necessary to probe, attack, or maintain presence in a cyber target.


network resilience
Definition: The ability of a network to:

  1. provide continuous operation (i.e., highly resistant to disruption and able to operate in a degraded mode if damaged);
  2. recover effectively if failure does occur;
  3. scale to meet rapid or unpredictable demands.

Network Services
Definition: A cybersecurity service that installs, configures, tests, operates, maintains, and manages networks and their firewalls, including hardware (e.g., hubs, bridges, switches, multiplexers, routers, cables, proxy servers, and protective distributor systems) and software that permit the sharing and transmission of all spectrum transmissions of information to support the security of information and information systems.

Definition: A property achieved through cryptographic methods to protect against an individual or entity falsely denying having performed a particular action related to data.

Extended Definition: Provides the capability to determine whether a given individual took a particular action such as creating information, sending a message, approving information, and receiving a message.

Related Term(s): integrity, authenticity


Definition: A passive information system-related entity containing or receiving information.

Related Term(s): subject, access, access control

Operate & Maintain
Definition: Cybersecurity service category consisting of specialty areas responsible for providing the support, administration, and maintenance necessary to ensure effective and efficient IT system performance and security.

operational exercise
Definition: An action-based exercise where personnel rehearse reactions to an incident scenario, drawing on their understanding of plans and procedures, roles, and responsibilities.

Extended Definition: Also referred to as operations-based exercise.

Operations Technology
Definition: The hardware and software systems used to operate industrial control devices.

Related Term(s): Industrial Control System

outside(r) threat
Definition: A person or group of persons external to an organization who are not authorized to access its assets and pose a potential risk to the organization and its assets.

Related Term(s): inside(r) threat

Oversight & Development
Definition: A cybersecurity service category consisting of specialty areas providing leadership, management, direction, and/or development and advocacy so that all individuals and the organization may effectively conduct cybersecurity work.

Open Web Application Security Project (OWASP)
Definition: An open community dedicated to enabling organizations to conceive, develop, acquire, operate, and maintain applications that can be trusted.


passive attack

Definition: An actual assault perpetrated by an intentional threat source that attempts to learn or make use of information from a system, but does not attempt to alter the system, its resources, its data, or its operations.

Related Term(s): active attack

Definition: A string of characters (letters, numbers, and other symbols) used to authenticate an identity or to verify access authorization.

pen test
Definition: A colloquial term for penetration test or penetration testing.

Synonym(s): penetration testing

Synonym(s): intrusion

penetration testing
Definition: An evaluation methodology whereby assessors search for vulnerabilities and attempt to circumvent the security features of a network and/or information system.

Personal Identifying Information / Personally Identifiable Information
Definition: The information that permits the identity of an individual to be directly or indirectly inferred.

Definition: A digital form of social engineering to deceive individuals into providing sensitive information.

Definition: Unencrypted information.

Related Term(s): ciphertext

Definition: An observable occurrence or sign that an attacker may be preparing to cause an incident.

Related Term(s): indicator

Definition: The activities to build, sustain, and improve readiness capabilities to prevent, protect against, respond to, and recover from natural or manmade incidents.

Definition: The assurance that the confidentiality of, and access to, certain information about an entity is protected.

Extended Definition: The ability of individuals to understand and exercise control over how information about themselves may be used by others.

private key
Definition: A cryptographic key that must be kept confidential and is used to enable the operation of an asymmetric (public key) cryptographic algorithm.

Extended Definition: The secret part of an asymmetric key pair that is uniquely associated with an entity.

Related Term(s): public key, asymmetric cryptography

Protect & Defend
Definition: A cybersecurity service category consisting of specialty areas responsible for the identification, analysis, and mitigation of threats to internal IT systems or networks.

public key
Definition: A cryptographic key that may be widely published and is used to enable the operation of an asymmetric (public key) cryptographic algorithm.

Extended Definition: The public part of an asymmetric key pair that is uniquely associated with an entity and that may be made public.

Related Term(s): private key, asymmetric cryptography

public key cryptography
Definition: A branch of cryptography in which a cryptographic system or algorithms use two uniquely linked keys: a public key and a private key (a key pair).

Synonym(s): asymmetric cryptography, public key encryption

public key encryption
Synonym(s): public key cryptography

Public Key Infrastructure
Definition: A framework consisting of standards and services to enable secure, encrypted communication and authentication over potentially insecure networks such as the Internet.

Extended Definition: A framework and services for generating, producing, distributing, controlling, accounting for, and revoking (destroying) public key certificates.




Definition: The activities after an incident or event to restore essential services and operations in the short and medium term and fully restore all capabilities in the longer term.

Red Team
Definition: A group authorized and organized to emulate a potential adversary’s attack or exploitation capabilities against an enterprise’s cybersecurity posture.

Related Term(s): Blue Team, White Team

Red Team exercise
Definition: An exercise, reflecting real-world conditions, that is conducted as a simulated attempt by an adversary to attack or exploit vulnerabilities in an enterprise's information systems.

Related Term(s): cyber exercise

Definition: Additional or alternative systems, sub-systems, assets, or processes that maintain a degree of overall functionality in case of loss or failure of another system, sub-system, asset, or process.

From: DHS Risk Lexicon

Definition: The ability to adapt to changing conditions and prepare for, withstand, and rapidly recover from disruption.

Definition: The activities that address the short-term, direct effects of an incident and may also support short-term recovery.

Extended Definition: In cybersecurity, response encompasses both automated and manual activities.

Related Term(s): recovery

response plan
Synonym(s): incident response plan

Definition: The potential for an unwanted or adverse outcome resulting from an incident, event, or occurrence, as determined by the likelihood that a particular threat will exploit a particular vulnerability, with the associated consequences.

risk analysis
Definition: The systematic examination of the components and characteristics of risk.

Related Term(s): risk assessment, risk

risk assessment
Definition: The product or process which collects information and assigns values to risks for the purpose of informing priorities, developing or comparing courses of action, and informing decision making.

Extended Definition: The appraisal of the risks facing an entity, asset, system, or network, organizational operations, individuals, geographic area, other organizations, or society, and includes determining the extent to which adverse circumstances or events could result in harmful consequences.

Related Term(s): risk analysis, risk

risk management
Definition: The process of identifying, analyzing, assessing, and communicating risk and accepting, avoiding, transferring or controlling it to an acceptable level considering associated costs and benefits of any actions taken.

Extended Definition: Includes: 1) conducting a risk assessment; 2) implementing strategies to mitigate risks; 3) continuous monitoring of risk over time; and 4) documenting the overall risk management program.

Related Term(s): enterprise risk management, integrated risk management, risk

risk mitigation
Synonym(s): mitigation

risk-based data management
Definition: A structured approach to managing risks to data and information by which an organization selects and applies appropriate security controls in compliance with policy and commensurate with the sensitivity and value of the data.

Definition: A set of software tools with administrator-level access privileges installed on an information system and designed to hide the presence of the tools, maintain the access privileges, and conceal the activities conducted by the tools.


secret key
Definition: A cryptographic key that is used for both encryption and decryption, enabling the operation of a symmetric key cryptography scheme.

Extended Definition: Also, a cryptographic algorithm that uses a single key (i.e., a secret key) for both encryption of plaintext and decryption of ciphertext.

Related Term(s): symmetric key

Securely Provision
Definition: A cybersecurity service category consisting of specialty areas concerned with conceptualizing, designing, and building secure IT systems, with responsibility for some aspect of the systems' development.

security automation
Definition: The use of information technology in place of manual processes for cyber incident response and management.

security incident
Synonym(s): incident

security policy
Definition: A rule or set of rules that govern the acceptable use of an organization's information and services to a level of acceptable risk and the means for protecting the organization's information assets.

Extended Definition: A rule or set of rules applied to an information system to provide security services.

Security Program Management
Definition: A Cybersecurity service that manages information security (e.g., information security) implications within the organization, specific program, or other area of responsibility, to include strategic, personnel, infrastructure, policy enforcement, emergency planning, security awareness, and other resources (e.g., the role of a Chief Information Security Officer).

Definition: A recognizable, distinguishing pattern.

Extended Definition: Types of signatures: attack signature, digital signature, electronic signature.

situational awareness
Definition: Comprehending information about the current and developing security posture and risks, based on information gathered, observation and analysis, and knowledge or experience.

Extended Definition: In cybersecurity, comprehending the current status and security posture with respect to availability, confidentiality, and integrity of networks, systems, users, and data, as well as projecting future states of these.

software assurance
Definition: The level of confidence that software is free from vulnerabilities, either intentionally designed into the software or accidentally inserted at any time during its lifecycle, and that the software functions in the intended manner.

Software Assurance and Security Engineering
Definition: Cybersecurity service that develops and writes/codes new (or modifies existing) computer applications, software, or specialized utility programs following software assurance best practices.

Definition: The abuse of electronic messaging systems to indiscriminately send unsolicited bulk messages.


Synonym(s): data spill, data breach

Definition: Faking the sending address of a transmission to gain illegal [unauthorized] entry into a secure system.

Extended Definition: The deliberate inducement of a user or resource to take incorrect action. Note: Impersonating, masquerading, piggybacking, and mimicking are forms of spoofing.

Definition: Software that is secretly or surreptitiously installed into an information system without the knowledge of the system user or owner.

Related Term(s): keylogger

SQL injection
Definition: Results from failure of the application to appropriately validate input. When specially crafted user-controlled input consisting of SQL syntax is used without proper validation as part of SQL queries, it is possible to glean information from the database in ways not envisaged during application design

Strategic Planning and Policy Development
Definition: Cybersecurity service that applies knowledge of priorities to define an entity.

Definition: An individual, process, or device causing information to flow among objects or a change to the system state.

Extended Definition: An active entity.

Related Term(s): object, access, access control

Supervisory Control and Data Acquisition
Definition: A generic name for a computerized system that is capable of gathering and processing data and applying operational controls to geographically dispersed assets over long distances.

Related Term(s): Industrial Control System

supply chain
Definition: A system of organizations, people, activities, information and resources, for creating and moving products including product components and/or services from suppliers through to their customers.

Related Term(s): supply chain risk management

Supply Chain Risk Management
Definition: The process of identifying, analyzing, and assessing supply chain risk and accepting, avoiding, transferring or controlling it to an acceptable level considering associated costs and benefits of any actions taken.

Related Term(s): supply chain

symmetric cryptography
Definition: A branch of cryptography in which a cryptographic system or algorithms use the same secret key (a shared secret key).

symmetric encryption algorithm
Synonym(s): symmetric cryptography

symmetric key
Definition: A cryptographic key that is used to perform both the cryptographic operation and its inverse, for example to encrypt plaintext and decrypt ciphertext, or create a message authentication code and to verify the code.

Extended Definition: Also, a cryptographic algorithm that uses a single key (i.e., a secret key) for both encryption of plaintext and decryption of ciphertext.

Related Term(s): secret key

System Administration
Definition: A cybersecurity service that installs, configures, troubleshoots, and maintains server configurations (hardware and software) to ensure their confidentiality, integrity, and availability; also manages accounts, firewalls, and patches; responsible for access control, passwords, and account creation and administration.

System hardening
Definition: A process to eliminate as many security risks as possible by removing all nonessential software programs, protocols, services and utilities from the system.

system integrity
Definition: The attribute of an information system when it performs its intended function in an unimpaired manner, free from deliberate or inadvertent unauthorized manipulation of the system.

Related Term(s): integrity, data integrity

Systems Development
Definition: A cybersecurity service that works on the development phases of the systems development lifecycle.

Systems Requirements Planning
Definition: A cybersecurity service that consults with customers to gather and evaluate functional requirements and translates these requirements into technical solutions; provides guidance to customers about applicability of information systems to meet business needs.

Systems Security Analysis
Definition: A cybersecurity service that conducts the integration/testing, operations, and maintenance of systems security.

Systems Security Architecture
Definition: Cybersecurity service that develops system concepts and works on the capabilities phases of the systems development lifecycle; translates technology and environmental conditions (e.g., law and regulation) into system and security designs and processes.


tabletop exercise

Definition: A discussion-based exercise where personnel meet in a classroom setting or breakout groups and are presented with a scenario to validate the content of plans, procedures, policies, cooperative agreements or other information for managing an incident.

tailored trustworthy space
Definition: A cyberspace environment that provides a user with confidence in its security, using automated mechanisms to ascertain security conditions and adjust the level of security based on the user's context and in the face of an evolving range of threats.

Definition: Cybersecurity service that applies current knowledge of one or more regions, countries, non-state entities, and/or technologies.

Technology Research and Development
Definition: Cybersecurity service that conducts technology assessment and integration processes; provides and supports a prototype capability and/or evaluates its utility.

Test and Evaluation
Definition: Cybersecurity service that develops and conducts tests of systems to evaluate compliance with specifications and requirements by applying principles and methods for cost-effective planning, evaluating, verifying, and validating of technical, functional, and performance characteristics (including interoperability) of systems or elements of systems incorporating information technology.

Definition: A circumstance or event that has or indicates the potential to exploit vulnerabilities and to adversely impact (create adverse consequences for) organizational operations, organizational assets (including information and information systems), individuals, other organizations, or society.

Extended Definition: Includes an individual or group of individuals, entity such as an organization or a nation), action, or occurrence.

threat actor

Synonym(s): threat agent

threat agent
Definition: An individual, group, organization, or government that conducts or has the intent to conduct detrimental activities.

Related Term(s): adversary, attacker

threat analysis
Definition: The detailed evaluation of the characteristics of individual threats.

Extended Definition: Cybersecurity service that Identifies and assesses the capabilities and activities of cyber criminals or foreign intelligence entities; produces findings to help initialize or support law enforcement and counterintelligence investigations or activities.

threat assessment
Definition: The product or process of identifying or evaluating entities, actions, or occurrences, whether natural or man-made, that have or indicate the potential to harm life, information, operations, and/or property.

Related Term(s): threat analysis

Definition: In access control, data that authenticates the identity of a client or a service and, together with a temporary encryption key (a session key), forms a credential.

traffic light protocol
Definition: A set of designations employing four colors (RED, AMBER, GREEN, and WHITE) used to ensure that sensitive information is shared with the correct audience.

Trojan horse
Definition: A computer program that appears to have a useful function, but also has a hidden and potentially malicious function that evades security mechanisms, sometimes by exploiting legitimate authorizations of a system entity that invokes the program.


UDP Scan

Definition: UDP scans perform scans to determine which UDP ports are open.

unauthorized access
Definition: Any access that violates the stated security policy.



Definition: A computer program that can replicate itself, infect a computer without permission or knowledge of the user, and then spread or propagate to another computer.

Related Term(s): macro virus

Voice Firewall
Definition: A physical discontinuity in a voice network that monitors, alerts and controls inbound and outbound voice network activity based on user-defined call admission control (CAC) policies, voice application layer security threats or unauthorized service use violations.

Voice Intrusion Prevention System (IPS)
Definition: Voice IPS is a security management system for voice networks which monitors voice traffic for multiple calling patterns or attack/abuse signatures to proactively detect and prevent toll fraud, Denial of Service, telecom attacks, service abuse, and other anomalous activity.

Definition: A characteristic or specific weakness that renders an organization or asset (such as information or an information system) open to exploitation by a given threat or susceptible to a given hazard.

Extended Definition: Characteristic of location or security posture or of design, security procedures, internal controls, or the implementation of any of these that permit a threat or hazard to occur. Vulnerability (expressing degree of vulnerability): qualitative or quantitative expression of the level of susceptibility to harm when a threat or hazard is realized.

Related Term(s): weakness

Vulnerability Assessment and Management
Definition: Cybersecurity service that conducts assessments of threats and vulnerabilities, determines deviations from acceptable configurations, enterprise or local policy, assesses the level of risk, and develops and/or recommends appropriate mitigation countermeasures in operational and non-operational situations.



Definition: A shortcoming or imperfection in software code, design, architecture, or deployment that, under proper conditions, could become a vulnerability or contribute to the introduction of vulnerabilities.

Related Term(s): vulnerability

White Team
Definition: A group responsible for refereeing an engagement between a Red Team of mock attackers and a Blue Team of actual defenders of information systems.

Related Term(s): Blue Team, Red Team

Definition: A list of entities that are considered trustworthy and are granted access or privileges.

Related Term(s): blacklist

work factor
Definition: An estimate of the effort or time needed by a potential adversary, with specified expertise and resources, to overcome a protective measure.

Definition: A self-replicating, self-propagating, self-contained program that uses networking mechanisms to spread itself.




Zero Day
Definition: "Zero Day" is the day a new vulnerability is made known. In some cases, a "zero day" exploit is referred to an exploit for which no patch is available yet. ("day one" - day at which the patch is made available).

Zero-day attack
Definition: A zero-day (or zero-hour or day zero) attack or threat is a computer threat that tries to exploit computer application vulnerabilities that are unknown to others or undisclosed to the software developer. Zero-day exploits (actual code that can use a security hole to carry out an attack) are used or shared by attackers before the software developer knows about the vulnerability.

Definition: A zombie computer (often shortened as zombie) is a computer connected to the Internet that has been compromised by a hacker, a computer virus, or a trojan horse. Generally, a compromised machine is only one of many in a botnet, and will be used to perform malicious tasks of one sort or another under remote direction. Most owners of zombie computers are unaware that their system is being used in this way. Because the owner tends to be unaware, these computers are metaphorically compared to zombies.