  Social bots represent a new generation of bots that make use of online social
networks (OSNs) as a command and control (C\&C) channel. Malicious social bots
were responsible for launching large-scale spam campaigns, promoting low-cap
stocks, manipulating user's digital influence and conducting political
astroturf. This paper presents a detailed review on current social bots and
proper techniques that can be used to fly under the radar of OSNs defences to
be undetectable for long periods of time. We also suggest a refined taxonomy of
detection approaches from social network perspective, as well as commonly used
datasets and their corresponding findings. Our study can help OSN
administrators and researchers understand the destructive potential of
malicious social bots and can improve the current defence strategies against
them.
