  Trolling and social bots have been proven as powerful tactics for
manipulating the public opinion and sowing discord among Twitter users. This
effort requires substantial content fabrication and account coordination to
evade Twitter's detection of nefarious platform use. In this paper we explore
an alternative tactic for covert social media interference by inducing
misperceptions about genuine, non-trolling content from verified users. This
tactic uses a malware that covertly manipulates targeted words, hashtags, and
Twitter metrics before the genuine content is presented to a targeted user in a
covert man-in-the-middle fashion. Early tests of the malware found that it is
capable of achieving a similar goal as trolls and social bots, that is,
silencing or provoking social media users to express their opinion in polarized
debates on social media. Following this, we conducted experimental tests in
controlled settings (N=315) where the malware covertly manipulated the
perception in a Twitter debate on the risk of vaccines causing autism. The
empirical results demonstrate that inducing misperception is an effective
tactic to silence users on Twitter when debating polarizing issues like
vaccines. We used the findings to propose a solution for countering the effect
of the malware-induced misperception that could also be used against trolls and
social bots on Twitter.
