  Social media, seen by some as the modern public square, is vulnerable to
manipulation. By controlling inauthentic accounts impersonating humans,
malicious actors can amplify disinformation within target communities. The
consequences of such operations are difficult to evaluate due to the challenges
posed by collecting data and carrying out ethical experiments that would
influence online communities. Here we use a social media model that simulates
information diffusion in an empirical network to quantify the impacts of
several adversarial manipulation tactics on the quality of content. We find
that the presence of influential accounts, a hallmark of social media,
exacerbates the vulnerabilities of online communities to manipulation. Among
the explored tactics that bad actors can employ, infiltrating a community is
the most likely to make low-quality content go viral. Such harm can be further
compounded by inauthentic agents flooding the network with low-quality, yet
appealing content, but is mitigated when bad actors focus on specific targets,
such as influential or vulnerable individuals. These insights suggest
countermeasures that platforms could employ to increase the resilience of
social media users to manipulation.
