XDR is the argument that most attacks are invisible to any single tool. The signals exist. They just sit in five different products that never compare notes.
The short answer
XDR stands for extended detection and response. It collects telemetry from endpoint, identity, cloud, network and email, correlates it into a single view, and provides response actions across all of them. The X is the point: it extends EDR beyond the endpoint so that a chain of individually unremarkable events can be recognised as one attack.
It is also a contested category. Every vendor defines it as roughly the shape of what they already sell, which makes the term harder to evaluate than it should be.
On this page
The five signal layers
XDR, EDR and SIEM
These three overlap enough that vendors sell all of them against each other. The honest distinction is about scope and about who does the work.
| EDR | XDR | SIEM | |
|---|---|---|---|
| Scope | Endpoints only | Endpoint plus identity, cloud, network, email | Anything that emits a log |
| Correlation | Within one host | Across domains, pre-built by the vendor | Whatever rules you write |
| Response | On the endpoint | Across the connected layers | Usually none by itself |
| Setup effort | Deploy an agent | Connect the sources it supports | Ingestion, parsing, tuning, ongoing |
| Best at | Depth on the host | Speed to a usable answer | Breadth, retention and custom questions |
SIEM is not obsolete and this does not replace it. SIEM will ingest anything, which matters for audit retention and for the odd log source nobody anticipated. The newer category trades that breadth for correlation that works on day one instead of after a tuning project.
Native XDR and open XDR
This is the actual buying decision, and it is where most evaluations go wrong.
| Native | Open | |
|---|---|---|
| Telemetry source | The vendor’s own modules | Third-party tools via connectors |
| Data consistency | One schema, designed together | Normalisation of whatever each tool exports |
| Detection quality | Higher, because the signals were built to be compared | Depends on what each connector exposes |
| Flexibility | You use the vendor’s modules | Keep the tools you already have |
| Failure mode | Lock-in to one stack | Correlation quietly degrades as a connector loses fidelity |
Correlation is only as good as the weakest connector
The open model sounds like the safer choice because it preserves existing investments. The catch is that a connector only surfaces what the source tool chose to export, which is rarely everything. When a vendor changes an API or drops a field, correlation degrades without anything visibly breaking. The native model avoids that by never leaving one schema, which is the strongest argument for buying detection from the same place you buy the controls.
What XDR is meant to fix
| Problem | What it looks like |
|---|---|
| Cross-domain blindness | Each tool sees a minor event. Nobody sees the chain that connects them |
| Alert volume | Five products each generating alerts, most of which are noise, all needing triage |
| Swivel-chair investigation | Answering one question requires four consoles and manual timestamp matching |
| Slow containment | Response means logging into a different tool for each action, at the worst possible moment |
| Missing context | An endpoint alert with no identity or cloud context is hard to prioritise honestly |
| Small teams | The work assumes a staffed security operations function, which most companies do not have |
That last row is why the category matters more to a lean team than to a large one. A big organisation can staff its way through fragmentation. A ten-person company cannot, so correlation has to come from the tooling.
How Osto delivers XDR
Osto is native XDR by construction rather than by strategy. Endpoint, identity, ZTNA, cloud posture, web and API protection and email security are all built in one stack, so the telemetry shares a schema before anything reaches the correlation layer. There are no connectors to maintain and no fields lost in translation.
The practical result is the scenario in the diagram. A phishing email delivered, a device flagged, a login from an unfamiliar location and a new cloud key created are four low-severity events in four separate products. In one stack they are a single chain with a single timeline, and containment happens in the same place. That correlation also feeds the incident response record, which is what an auditor asks for under SOC 2 and what the Detect and Respond functions of NIST CSF describe.
Platform walkthrough
Four low alerts, or one incident
Endpoint, identity, cloud, network and email built in one stack, so correlation happens without connectors to maintain. One owner, one dashboard.
Book a demoNative correlation, no connectors · Built for lean teams · One platform, everything
Frequently asked questions
What is XDR?
Extended detection and response. It gathers telemetry from endpoint, identity, cloud, network and email, correlates it centrally, and offers response actions across those layers. It extends EDR beyond the single host.
What is the difference between XDR and EDR?
EDR sees one endpoint deeply. XDR sees multiple domains and connects events between them. An attack that starts in email, moves through identity and ends in cloud is only visible as one thing at the XDR layer.
Does XDR replace SIEM?
Not usually. SIEM ingests any log source and holds it for retention and custom queries, which matters for audit. XDR gives correlation that works immediately across a defined set of domains. Many organisations run both, with XDR handling detection and SIEM handling breadth.
What is the difference between native and open XDR?
Native XDR correlates telemetry from a single vendor’s own modules, so the data shares one schema. Open XDR connects third-party tools, preserving existing investments but depending on what each connector exposes. Native generally detects better, open is more flexible.
Is it the same as MDR?
No. Extended detection and response is technology. MDR, managed detection and response, is a service where an external team operates detection on your behalf. You can buy MDR delivered on top of XDR, and the two terms are frequently blurred in marketing.