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What Detection Engineering Is
TheoryBeginner13 minDetection Engineering

Use Cases & Detection Hypotheses

What is it?

A detection hypothesis is a testable statement of the form 'if technique T happens in our environment, it would appear in telemetry as observable O'. It bridges a threat behavior and a concrete detection: name the behavior, predict its telemetry footprint, and that prediction becomes the logic's target.

Why it matters

The hypothesis is what makes a detection buildable and testable: it says exactly what to look for and where, so the logic and the test cases both follow from it.

Where you see it

The bridge from a threat-informed requirement to concrete detection logic.

What normal looks like

A hypothesis predicting a specific, checkable telemetry observable for a named technique.

What suspicious looks like

Not applicable directly.

How analysts investigate

By writing the hypothesis explicitly (technique → predicted observable → data source), then deriving both the detection logic and its test cases from it.

Common beginner mistakes

  • Writing logic before the hypothesis — without a predicted observable, there is nothing to test the rule against and no way to know it works.
Hypothesis to logic
TelemetryCondition / Thresholddetection logicAlertNo AlertFalse Positive — alert fires, activity is actually benignFalse Negative — real activity, but no alert fires
A detection hypothesis predicts a telemetry observable; the logic and the test cases both derive from that prediction.

Quick check

Which is a well-formed detection hypothesis?

A quick self-check — it doesn't affect your XP or progress.

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