What is XDR?
XDR (Extended Detection and Response) is a security platform that collects telemetry from multiple domains, such as endpoints, network, email, identities, cloud and OT, automatically correlates it into incidents and lets you respond from a single console. Where EDR only sees what happens on one computer, XDR connects a phishing email, a suspicious sign-in and a process on a server. XDR is therefore a step beyond EDR and an alternative or complement to a standalone SIEM within an organisation’s cybersecurity.
🧠 How does XDR work?
An XDR platform goes through four steps, usually within a single vendor ecosystem:
- Collect - sensors deliver telemetry: an agent on endpoints, network sensors (NDR), email security, identity systems such as Active Directory and logs from cloud environments
- Normalise - all data lands in one data model, so a user name or IP address can be recognised across sources
- Correlate - individual alerts are merged into one incident with a timeline, often mapped to MITRE ATT&CK techniques and enriched with threat intelligence such as IOCs and TTPs
- Respond - the analyst (or an automatic rule) isolates an endpoint, disables an account, removes an email from every mailbox or pushes a firewall rule
The main advantage lies in correlation. An attack that relies on living off the land leaves little that looks suspicious in any single source, but the combination of an unusual sign-in, a PowerShell command and lateral movement does stand out. As a result, a SOC analyst has to stitch fewer separate alerts together by hand.
🕰️ Where does the term XDR come from?
The term XDR was introduced in 2018 by Nir Zuk, co-founder and CTO of Palo Alto Networks, in response to EDR tools that only looked at endpoints. Other vendors soon followed. Gartner initially described XDR as a SaaS-based, vendor-specific platform that natively integrates multiple of the vendor’s own security products. The Market Guide for XDR of August 2023 broadened that definition: XDR must have its own native sensors, but may run on-premises as well as SaaS. As a minimum, Gartner names an endpoint sensor plus at least one other native security sensor with prebuilt integration.
The market distinguishes two variants:
| Variant | Characteristic | Advantage | Drawback |
|---|---|---|---|
| Native XDR | All sensors and the console from one vendor | Deep integration, fast response, one agent | Vendor lock-in |
| Open or hybrid XDR | Also connects third-party products through APIs | Existing investments remain useful | Quality depends on each integration |
For OT environments the open variant is often the only realistic option, because OT network sensors usually come from a specialist vendor.
🔄 What is the difference between XDR, EDR, SIEM and SOAR?
| Characteristic | EDR | SIEM | SOAR | XDR |
|---|---|---|---|---|
| Focus | Endpoints | Logs from all sources | Automating response | Detection and response across domains |
| Data sources | Own agent | Any vendor, via connectors | Alerts from SIEM, XDR and tickets | Mainly own sensors, supplemented by third parties |
| Detection | Behaviour on the endpoint | Correlation rules you maintain | No detection of its own | Prebuilt correlation across sources |
| Response | Isolate host, kill process | Limited, via integrations | Playbooks across many tools | Built in per domain |
| Log retention | Weeks to months | Long, also for compliance | Not applicable | Usually shorter than a SIEM |
In practice the categories complement each other. A SIEM remains strong in long-term log retention and data from every vendor, while XDR is stronger in fast detection within its own ecosystem. Many vendors now bundle SIEM, SOAR and XDR into one platform.
🧱 What does an XDR platform include?
| Function | Examples |
|---|---|
| Endpoint detection | EDR agent on workstations and servers: processes, memory, behaviour |
| Network analysis | NDR: lateral movement, command and control, unusual connections |
| Email security | Detecting and recalling phishing, spoofing and malicious attachments |
| Identity | Suspicious sign-ins, abuse of admin accounts, integration with IAM |
| Cloud | Monitoring activity in IaaS and SaaS environments |
| Threat intelligence | IOCs, TTPs and real-time feeds from the vendor |
| Automated response | Isolation, blocking, alerting and remediation |
🏭 How do you use XDR in OT environments?
XDR comes from the IT world, but is increasingly extended to ICS environments. Different rules apply there:
- No agents on controllers - an XDR agent cannot run on a PLC or RTU. Only Windows systems such as HMI servers, SCADA servers and the engineering station qualify, and only with the approval of the plant’s supplier.
- Passive network sensors as a source - OT visibility comes from passive monitoring that dissects industrial protocols such as Modbus and DNP3. Products such as Nozomi, Claroty, Dragos, Tenable OT and Microsoft Defender for IoT forward their alerts to the XDR or SIEM platform.
- Behavioural baselines - industrial processes are predictable, so a new connection or an unexpected write command to a PLC is a strong signal. MITRE ATT&CK for ICS helps interpret those alerts.
- Cautious response - automatically isolating an HMI can leave the operator blind to the process. In OT, response is therefore usually manual and agreed with the person responsible for the process.
- Asset context - link alerts to the asset inventory, so an analyst knows whether a system is a coffee machine or a safety system.
The greatest risk lies at the boundary between IT and OT. XDR adds value there, because it can follow an attack from a phishing email in the office to a suspicious session on a jump server in the OT network.
🚀 Which XDR platforms are available?
| Platform | Vendor | Notable feature |
|---|---|---|
| Microsoft Defender XDR | Microsoft | Called Microsoft 365 Defender until November 2023; OT visibility through Defender for IoT |
| Cortex XDR | Palo Alto Networks | Also built into Cortex XSIAM, the platform QRadar SaaS customers are migrating to |
| Falcon Insight XDR | CrowdStrike | Builds on the Falcon endpoint agent |
| Singularity XDR | SentinelOne | Strong in autonomous response on endpoints |
| Trend Vision One | Trend Micro | Combines endpoint, email, network and cloud |
| Sophos XDR | Sophos | Often bought as a managed service (MDR) |
| Elastic Security | Elastic | Combines SIEM and XDR on top of Elasticsearch |
The term XDR is used loosely in marketing. When choosing, ask which sources are supported natively and which only arrive through a separate connector.
🧭 How do you introduce XDR step by step?
- Decide on the sources - start with endpoints, email and identity; that is where most attacks begin, including ransomware.
- Choose native or open - list the security products you already have and how well they integrate.
- Arrange staffing - XDR needs analysts who follow up alerts 24/7, in-house or through a (managed) SOC or OT SOC.
- Agree on response - record in an incident response plan which actions may run automatically and which systems, such as OT, are never isolated automatically.
- Test agent updates - the faulty CrowdStrike Falcon content update of 19 July 2024 crashed around 8.5 million Windows systems worldwide. Roll out updates to OT in phases.
- Use the data for hunting - threat hunting on XDR data produces new detection rules.
For Dutch organisations under NIS2 and the Cybersecurity Act, in force since 15 August 2026, XDR supports the incident reporting obligation: an early warning within 24 hours and an incident notification within 72 hours require fast detection and a clear timeline.
❓ Frequently asked questions
What does XDR stand for?
XDR stands for Extended Detection and Response. The term was introduced in 2018 by Nir Zuk of Palo Alto Networks. “Extended” refers to expanding endpoint detection to the network, email, identity and cloud.
Does XDR replace a SIEM?
XDR can partly replace a SIEM, especially in smaller organisations with one dominant vendor. A SIEM remains stronger at retaining logs over long periods and processing data from every vendor. Larger organisations therefore often use both, or a platform that combines SIEM and XDR.
What is the difference between XDR and MDR?
XDR is technology: a platform that combines detection and response across multiple domains. MDR (Managed Detection and Response) is a service in which an external provider carries out that detection and response for you 24/7. Many MDR services run on an XDR platform.
Can XDR be used in OT networks?
XDR can monitor OT networks, but not with an agent on PLCs or RTUs. OT visibility comes from passive network sensors that understand industrial protocols and pass their alerts on to the XDR platform. Automated response is used sparingly in OT so that the process is not disrupted.
Is XDR mandatory under NIS2?
NIS2 and the Dutch Cybersecurity Act do not prescribe a specific product such as XDR. They do require appropriate measures for detection and incident handling, and reporting within 24 hours, 72 hours and one month. XDR is one way to meet those requirements.
What is the difference between native and open XDR?
Native XDR uses only sensors and software from one vendor, which gives deep integration but creates dependency. Open or hybrid XDR also connects third-party products through APIs. In OT environments open XDR is often necessary, because the OT sensors come from specialist vendors.
📌 In summary
XDR brings detection and response across endpoints, network, email, identity, cloud and OT together in one security platform, so attacks become visible as a single coherent incident. In OT, XDR works through passive network sensors rather than agents, with cautious response, so that security does not disrupt the physical process.