Hypothesis-driven investigation is a threat-hunting method that begins with a testable suspicion, such as "an attacker may be using valid accounts to move quietly" or "this host may be beaconing to a command server." Defenders then collect telemetry, logs, and context to confirm or reject that idea.
This matters because security teams rarely have unlimited time to inspect every event. A clear hypothesis focuses the hunt, reduces noise, and turns vague concern into measurable checks. In real attacks, this approach helps analysts look for small clues that seem harmless alone, like unusual login timing, odd process chains, or rare network destinations. In defense, it also exposes gaps: if the evidence is missing, that may reveal weak logging, poor baselines, or blind spots in visibility.