A policy hook is a checkpoint in a software workflow where a security rule can inspect, approve, modify, or block an action before it is executed. It is commonly used in runtime enforcement layers, API gateways, and agent control systems to make sure actions match identity, context, and policy.
In cyber security, policy hooks matter because many attacks succeed at the point of action, not at the point of generation. For example, an AI agent may be prompted to call a tool, access a file, or send a request that exceeds its permissions. A policy hook can stop that step, require human approval, or log the event for an audit trail. Defenders use hooks to enforce least privilege, limit unsafe tool use, and detect context manipulation. Attackers may try to bypass or confuse the hook by hiding intent in prompts, changing context, or triggering actions that look normal but are risky. The value of a policy hook is that it turns security from a passive review into an active control point.