Denial of service (DoS) attacks

1. An attack that prevents or impairs the authorized use of information system resources or services.

Source: Explore Terms: A Glossary of Common Cybersecurity Terminology, National Initiative for Cybersecurity Careers and Studies (NICCS),

2. The prevention of authorized access to resources or the delating of time-critical operations.

Source: The State and Local Election Cybersecurity Playbook, Defending Digital Democracy Project, Harvard Kennedy School Belfer Center for Science and International Affairs,

3. A DoS attack is an automated attempt to “flood” or overwhelm an organization’s server or website with requests, causing it to be unavailable to legitimate users.

Source: Guide to Cybersecurity as Risk Management: The Role of Elected Officials, Governing Institute, CGI,

4. An attempt to overwhelm a server’s capacity with traffic so that it is unable to perform its usual duties and respond to its intended users.

Source: Independent Panel on Internet Voting, British Columbia,

5. Have the goal of causing a loss of a specific service to users or at least to considerably restrict the accessibility of the service.

Source: Information Assurance Situation in Switzerland and Internationally, Reporting and Analysis Centre for Information Assurance MELANI,

6. A type of cyber action designed to prevent users from accessing a network-connected service by sending legitimate requests from one source to overload a network’s resources.

Source: U.S. Cyberspace Solarium Commission, March 2020,