Social media trolling is a powerful tactic to manipulate public opinion on issues with a high moral component. Troll farms, as evidenced in the past, created fabricated content to provoke or silence people to share their opinion on social media during the US presidential election in 2016. In this paper, we introduce an alternate way of provoking or silencing social media discourse by manipulating how users perceive authentic content. This manipulation is performed by man-in-the-middle malware that covertly rearranges the linguistic content of an authentic social media post and comments. We call this attack Malware-Induced Misperception (MIM) because the goal is to socially engineer spiral-of-silence conditions on social media by inducing perception. We conducted experimental tests in controlled settings (N = 311) where a malware covertly altered selected words in a Facebook post about the freedom of political expression on college campuses. The empirical results (1) confirm the previous findings about the presence of the spiral-of-silence effect on social media; and (2) demonstrate that inducing misperception is an effective tactic to silence or provoke targeted users on Facebook to express their opinion on a polarizing political issue.