What is the final stage of the Cyber Kill Chain where the adversary implements their goals?

The final stage of the Cyber Kill Chain is indeed where the adversary implements their goals, which corresponds to "Actions on Objectives." At this stage, the attacker has already established access to the target system and is ready to carry out their intended malicious actions. This could involve stealing sensitive data, deploying further malware, or disrupting services, depending on the adversary's motivations.

The stages that precede this—such as Command and Control, Installation, and Exploitation—are crucial for gaining and maintaining access to the target environment. However, it is during the Actions on Objectives stage that the adversary achieves the ultimate goals they set out to accomplish at the onset of the attack. This makes it the culmination of the entire attack process as it reflects the successful attainment of their initial objectives.