Two-factor authentication can be circumvented through which of the following attacks?
A man-in-the-middle attack is similar to piggybacking, in that the attacker pretends to be the
legitimate destination, and then merely retransmits whatever is sent by the authorized user along
with additional transactions after authentication has been accepted. A denial-of- service attack does
not have a relationship to authentication. Key logging and brute force could circumvent a normal
authentication but not a two-factor authentication.