Digital fingerprinting for identifying malicious collusive groups on Twitter.

Propagation of malicious code on online social networks (OSNs) is often a coordinated effort by collusive groups of malicious actors hiding behind multiple online identities (or digital personas). Increased interaction in OSN has made them reliable for the efficient orchestration of cyberattacks such as phishing click bait and drive-by downloads. URL shortening enables obfuscation of such links to malicious websites and massive interaction with such embedded malicious links in OSN guarantees maximum reach. These malicious links lure users to malicious endpoints where attackers can exploit system vulnerabilities. Identifying the organized groups colluding to spread malware is non-trivial owing to the fluidity and anonymity of criminal digital personas on OSN. This paper proposes a methodology for identifying such organized groups of criminal actors working together to spread malicious links on OSN. Our approach focuses on understanding malicious users as 'digital criminal personas' and characteristics of their online existence. We first identify those users engaged in propagating malicious links on OSN platforms, and further develop a methodology to create a digital fingerprint for each malicious OSN account/digital persona. We create similarity clusters of malicious actors based on these unique digital fingerprints to establish 'collusive' behaviour. We evaluate the ability of a cluster-based approach on OSN digital fingerprinting to identify collusive behaviour in OSN by estimating within-cluster similarity measures and testing it on a ground-truth dataset of five known colluding groups on Twitter. Our results show that our digital fingerprints can identify 90% of cyber personas engaged in collusive behaviour and 75% of collusion in a given sample set.