A Taxonomy for Threat Actors' Delivery Techniques

The main contribution of this paper is to provide an accurate taxonomy for delivery techniques, which allows the detection of novel techniques and the identification of appropriate countermeasures. Delivery is a key stage for offensive cyber operations. During delivery, a threat actor tries to gain an initial foothold into the targeted infrastructure. It is the first step of an offensive cyber operation, where the threat actor interacts with its victim in a hostile way; thus, its success is mandatory for the global achievement of the operation. However, delivery techniques are not well structured among the literature, being in many cases a simple list of techniques with which, if one of them is slightly modified by the threat actor, its detection becomes very difficult. This situation hinders the modeling of hostile actors, a fact that makes it difficult to identify countermeasures to detect and neutralize their malicious activities. In this work, we analyze the current delivery techniques' classification approaches and the problems linked to them. From this analysis, we propose a novel taxonomy that allows the accurate classification of techniques, overcoming the identified problems and allowing both the discovery of new techniques and the detection of gaps in deployed countermeasures. Our proposal significantly reduces the amount of effort needed to identify, analyze, and neutralize hostile activities from advanced threat actors, in particular their initial access stage. It follows a logical structure that can be easy to expand and adapt, and it can be directly used in the industry's commonly accepted standards, such as MITRE ATT&CK.