Basic Concept: AI systems that access file systems or databases use service accounts to authenticate. Applying the principle of least privilege to these service accounts limits the damage that can result from prompt injection or other attacks that cause the AI to perform unauthorized file access. CompTIA SecAI+ Study Guide covers least privilege as a core AI security control.

Why D is Correct: Reducing the privilege scope of the service account implements the least privilege principle, ensuring the AI system can only access files it legitimately needs for its intended function. If an attacker uses prompt injection to abuse the file search capability, the service account ' s limited permissions prevent access to sensitive files outside the defined scope, containing the blast radius of any exploitation.

Why A is Wrong: Custom detection rules identify anomalous behavior after it occurs. They are detective controls, not preventive controls. They do not stop an attacker from successfully abusing the system; they only alert after abuse has occurred.

Why B is Wrong: VPC segmentation isolates the workload at the network level, limiting lateral movement. However, it does not restrict what files the AI ' s service account can access within its own environment, so file abuse attacks within the segment are still possible.

Why C is Wrong: LLM guardrails filter prompt inputs and outputs for policy violations. While useful, they can potentially be bypassed through sophisticated prompt injection. Reducing service account privileges provides a defense-in-depth layer that limits damage even if guardrails are bypassed.