Dark web

Web sites that are not indexed by search engines and are only accessible through special networks such as The Onion Router (ToR). Often, the dark web is used by website operators who want to remain anonymous. The ‘dark web’ is a subset of the ‘deep web’.


The basic element that can be processed or produced by a computer to convey information.

Data at rest

Information that resides on media or a system.

Data breach

The unauthorised movement or disclosure of sensitive private or business information.

Data dump

A large amount of data transferred from one system or location to another.

Data encryption algorithm

Algorithms that are used to encrypt and decrypt data. This algorithm type is used for encrypting data to encrypt and decrypt various parts of the message, including the body content and the signature.

Data in transit

Information that is being communicated across a communication medium.

Data protection

Data protection is the process of safeguarding important information from corruption, compromise or loss.

Data repository

A location in which data is stored, managed and made available to users.

Data spill

The accidental or deliberate exposure of information into an uncontrolled or unauthorised environment, or to people without a need to know that information.


Database management system


Distributed control system


Distributed Denial-of-Service


Data encryption algorithm


A process whereby information is reduced to an OFFICIAL level and an administrative decision is made to formally authorise its release to the public.

Decrypting RSA with Obsolete and Weakened eNcryption (DROWN)

A cross-protocol security bug that attacks servers supporting modern SSLv3/TLS protocol suites by using their support for the obsolete, insecure SSL v2 protocol to leverage an attack on connections using up-to-date protocols that would otherwise be secure.


The decoding of encrypted messages.

Deep web

The part of the internet that is not indexed by search engines. Includes websites that are password-protected and paywalled, as well as encrypted networks, and databases.

Default passwords

Where a device needs a username and/or password to log in, a default password is usually provided that allows the device to be accessed during its initial setup, or after resetting it to factory defaults.

Defence in depth

The implementation of multiple layers of controls in a system to provide redundancy in the event a control fails or a vulnerability is exploited.

Defence Intelligence Organisation (DIO)

An Australian Government intelligence agency responsible for strategic and technical intelligence assessments, used to advise defence and government decision-making on national security and international security issues, and the planning and conduct of Australian Defence Force operations.


An electrical device or permanent magnet assembly which generates a coercive magnetic force for the purpose of degaussing magnetic storage devices.


A process for reducing the magnetism of a magnetic storage device to zero by applying a reverse (coercive) magnetic force. By doing this, any previously stored information is rendered unreadable.

Demilitarised zone (DMZ)

A small network with one or more servers that is kept separate from the core network, typically on the outside of the firewall or as a separate network protected by the firewall. Demilitarised zones usually provide information to less trusted networks, such as the internet.

Denial of service

When legitimate users are denied access to computer services (or resources), usually by overloading the service with requests.

Denial-of-service attack

A denial-of-service (DoS) attack is an attempt by a malicious actor to prevent legitimate access to online services (typically a website), for example, by consuming the amount of available bandwidth or the processing capacity of the server hosting the online service.

Department of Home Affairs

The Australian Government interior ministry with responsibilities for national security, law enforcement, emergency management, border control, immigration, refugees, citizenship, and multicultural affairs.

Device access control software

Software that can be used on a system to restrict access to communications ports. Device access control software can block all access to a communications port or allow access based on device types, manufacturer’s identification or even unique device identifiers.




Department of Home Affairs

Dictionary attack

Where attackers use ‘password dictionaries’ or long lists of the most commonly-used passwords and character combinations against a password in order to guess it and break into a system.

Digital certificate

An electronic document used to identify an individual, a system, a server, a company, or some other entity, and to associate a public key with the entity. A digital certificate is issued by a certification authority and is digitally signed by that authority.

Digital footprint

The unique set of traceable activities, actions, contributions and communications that are manifested on the internet or on digital devices.

Digital preservation

The coordinated and ongoing set of processes and activities that ensure long-term, error-free storage of digital information, with means for retrieval and interpretation, for the entire time the information is required.

Digital signature

A cryptographic process that allows the proof of the source (with non-repudiation) and the verification of the integrity of that data.

Digital Transformation Agency (DTA)

An Australian Government agency whose role is to make it easy for people to deal with government, by helping government agencies transform services to be simple, clear and fast.


Defence Intelligence Organisation


A device that allows data to flow in only one direction.

Disaster recovery

A set of policies, tools and procedures to enable the recovery or continuation of vital technology infrastructure and systems following a natural or human-induced disaster. Disaster recovery focuses on the IT or technology systems supporting critical business functions, as opposed to business continuity.

Distributed denial-of-service (DDoS) attack

A distributed denial-of-service (DDoS) attack is where the source is comprised of multiple, distributed unique IP addresses used to flood the bandwidth or resources of a targeted system or network.


DomainKeys Identified Mail


Direct Memory Access


Domain-based Message Authentication, Reporting and Conformance


Domain Name System


In the internet, a part of a naming hierarchy which consists of a sequence of names (labels) separated by periods (dots).

Note: There are multiple other technical and communications-related definitions for ‘domain’.

Domain Name System (DNS)

The naming system that translates domain names into IP addresses.

Domain-based Message Authentication, Reporting and…

An email authentication protocol designed to give email domain owners the ability to protect their domain from unauthorised use, commonly known as email spoofing.

DomainKeys Identified Mail (DKIM)

A system for authenticating emails that works with modern Message Transfer Agent systems. This resource was created to help fight spam, and uses a digital signature to help email recipients determine whether an email is legitimate.


Denial of Service

DoS attacks

Denial of Service attacks


A type of Trojan that downloads other malware onto a computer. The downloader needs to connect to the internet to download the files.


Obtaining and publishing private or personally identifiable information about an individual over the internet. Information can be obtained through a range of methods including network compromise, social engineering, data breaches, or research.

Drive-by download attacks

The unintentional download of malicious code to a computer or mobile device that leaves the user open to an attack. The user does not have to click on anything, download or open a malicious email attachment to have their computer or device infected.


Software that interfaces a hardware device with an operating system.


A type of Trojan that installs other malware files onto a computer or device. The other malware is included within the Trojan file, and does not require connection to the internet.


Decrypting RSA with Obsolete and Weakened eNcryption


A free and open-source web content management framework written in PHP and distributed under the GNU General Public License.


Digital Signature Algorithm


Digital Transformation Agency

Dual-stack network device

ICT equipment that implements both Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6) protocol stacks.