What Is XDR?

Extended detection and response correlates telemetry across several domains — endpoint, identity, email, cloud, network — within a single platform, so that signals too weak to alert individually combine into something worth investigating.

It grew out of endpoint detection as vendors added adjacent telemetry, and its value is breadth of correlation rather than depth in any one domain.

Why correlation across domains matters

A sign-in from an unfamiliar country is weak on its own; corporate travel produces it constantly. A process reading browser credential storage is weak on its own; password managers do it. An outbound connection to a new address is weak on its own.

The three together, on the same machine, within ten minutes, are not weak at all. Correlation converts a set of individually dismissible events into one high-confidence detection, which is the whole argument for the category.

How it differs from a log platform

A SIEM ingests anything and requires you to build the detection content. A platform in this category ships the correlation for its own telemetry and needs far less engineering, in exchange for covering only what it integrates with.

The trade is effort against coverage. For an organisation without detection engineering capacity, that trade is usually worth making; for one with unusual systems or heavy compliance logging requirements, it will not cover everything.

The single-vendor question

Correlation works best when the vendor controls the telemetry, which pushes toward consolidating endpoint, email and identity with one supplier. That improves detection and concentrates dependency.

Open variants integrate third-party sources and correlate less tightly. Neither answer is wrong, and the decision deserves to be made explicitly rather than arrived at through a series of individually sensible purchases.

What it does not remove

It does not remove the need for analysts. It reduces alert volume and improves alert quality, and somebody still has to investigate what it raises and decide what to do.

It also does not remove the need for log retention beyond its own window, which is frequently shorter than an investigation requires and shorter than compliance obligations specify.

Where it leaves your existing log platform

Adopting one of these platforms rarely removes the need for a SIEM, because compliance obligations, custom applications, network devices and industrial systems still generate logs the platform will not ingest.

The common end state is division of labour: the platform handles detection across the telemetry it owns, and the log platform handles retention, compliance reporting and the sources nothing else covers. That is more sustainable than either replacing the log platform outright or running two full detection programmes in parallel — and it means the log platform licence should shrink rather than disappear, which is worth modelling before the renewal conversation.

One practical caution during evaluation: these platforms are demonstrated against curated attack scenarios that exercise exactly the correlations they ship with. Asking a vendor to walk through a technique relevant to your own estate, rather than watching the standard demonstration, is a better test of whether the correlation reaches the activity you care about.

Where to start

List which telemetry sources are genuinely connected today. Correlation across one domain is endpoint detection with a different label.

See XDR versus SIEM. GuardsArm delivers managed detection and response.