The Cyber Kill Chain is a framework for understanding and responding to cyberattacks. It describes seven stages that an attacker must complete in order to successfully compromise a system.
In this case, the malicious actor has already gained access to the internal network through social engineering. This means that the actor has completed the Reconnaissance and Delivery stages of the Cyber Kill Chain. The actor is now in the Exploitation stage, where they are attempting to gain control of the system.