A large financial services firm recently released information regarding a security breach within its corporate
network that began several years before. During the time frame in which the breach occurred, indicators show
an attacker gained administrative access to the network through a file downloaded from a social media site and
subsequently installed it without the user's knowledge. Since the compromise, the attacker was able to take
command and control of the computer systems anonymously while obtaining sensitive corporate and personal
employee information. Which of the following methods did the attacker most likely use to gain access?


A. A bot
B. A fileless virus
C. A logic bomb
D. A RAT