A Literature Review on Mining Cyberthreat Intelligence from Unstructured Texts

Cyberthreat defense mechanisms have become more proactive these days, and thus leading to the increasing incorporation of cyberthreat intelligence (CTI). Cybersecurity researchers and vendors are powering the CTI with large volumes of unstructured textual data containing information on threat events, threat techniques, and tactics. Hence, extracting cyberthreat-relevant information through text mining is an effective way to obtain actionable CTI to thwart cyberattacks. The goal of this research is to aid cybersecurity researchers understand the source, purpose, and approaches for mining cyberthreat intelligence from unstructured text through a literature review of peer-reviewed studies on this topic. We perform a literature review to identify and analyze existing research on mining CTI. By using search queries in the bibliographic databases, 28,484 articles are found. From those, 38 studies are identified through the filtering criteria which include removing duplicates, non-English, non-peer-reviewed articles, and articles not about mining CTI. We find that the most prominent sources of unstructured threat data are the threat reports, Twitter feeds, and posts from hackers and security experts. We also observe that security researchers mined CTI from unstructured sources to extract Indicator of Compromise (IoC), threat-related topic, and event detection. Finally, natural language processing (NLP) based approaches: topic classification; keyword identification; and semantic relationship extraction among the keywords are mostly availed in the selected studies to mine CTI information from unstructured threat sources.