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A form of active wiretapping attack in which the attacker intercepts and selectively modifies communicated data to masquerade as one or more of the entities involved in a communication association.
CNSSI 4009-2015 from IETF RFC 4949 Ver 2
An attack in which an attacker is positioned between two communicating parties in order to intercept and/or alter data traveling between them. In the context of authentication, the attacker would be positioned between claimant and verifier, between registrant and CSP during enrollment, or between subscriber and CSP during authenticator binding.
NIST SP 1800-21B under Person (Man)-in-the-Middle Attack from NIST SP 800-63-3
NIST SP 800-63-3 under Man-in-the-Middle Attack (MitM)
An attack where the adversary positions himself in between the user and the system so that he can intercept and alter data traveling between them.
NISTIR 7711 under Man-In-The-Middle