1. An attempt to gain unauthorized access to system services, resources, or information, or an attempt to compromise system integrity, availability, or confidentiality. NIST SP 800-82 Rev. 2 (CNSSI 4009).
Source: The State and Local Election Cybersecurity Playbook, Defending Digital Democracy Project, Harvard Kennedy School Belfer Center for Science and International Affairs, https://www.belfercenter.org/sites/default/files/files/publication/StateLocalPlaybook%201.1.pdf; The Cyber Glossary, National Security Archive, George Washington University, https://nsarchive.gwu.edu/news/cyber-vault/2018-09-19/cyber-glossary; Explore Terms: A Glossary of Common Cybersecurity Terminology National Initiative for Cybersecurity Careers and Studies (NICCS), https://niccs.us-cert.gov/about-niccs/glossary
2. The intentional act of attempting to bypass one or more security services or controls of an information system.
Source: Explore Terms: A Glossary of Common Cybersecurity Terminology, National Initiative for Cybersecurity Careers and Studies (NICCS), https://niccs.us-cert.gov/about-niccs/glossary