  Over the past years, political events and public opinion on the Web have been
allegedly manipulated by accounts dedicated to spreading disinformation and
performing malicious activities on social media. These accounts hereafter
referred to as "Pathogenic Social Media (PSM)" accounts, are often controlled
by terrorist supporters, water armies or fake news writers and hence can pose
threats to social media and general public. Understanding and analyzing PSMs
could help social media firms devise sophisticated and automated techniques
that could be deployed to stop them from reaching their audience and
consequently reduce their threat. In this paper, we leverage the well-known
statistical technique "Hawkes Process" to quantify the influence of PSM
accounts on the dissemination of malicious information on social media
platforms. Our findings on a real-world ISIS-related dataset from Twitter
indicate that PSMs are significantly different from regular users in making a
message viral. Specifically, we observed that PSMs do not usually post URLs
from mainstream news sources. Instead, their tweets usually receive large
impact on audience, if contained URLs from Facebook and alternative news
outlets. In contrary, tweets posted by regular users receive nearly equal
impression regardless of the posted URLs and their sources. Our findings can
further shed light on understanding and detecting PSM accounts.
