SIEM vs SOAR vs XDR: Differences and How to Combine

SIEM, SOAR and XDR are the three acronyms that get mixed up the most in any conversation about modern defence, and also the ones that generate the most confusion in RFPs and proposals. All three promise to "detect and respond", all three overlap partially and all three sell the same pitch. The real difference is subtle but important: SIEM centralises and correlates logs, SOAR automates response and XDR detects and contains threats in an integrated way across endpoint, network, identity and cloud. They aren't three alternative purchases: in a mature SOC, they work together and solve different problems. This piece compares the three with operational definitions, real use cases and concrete guidance to decide which fits each maturity level and company size.

Quick definitions

SIEM (Security Information and Event Management)

Centralises logs and events from across the infrastructure (endpoints, network, identities, applications, cloud, SaaS), normalises them to a common format and applies correlation rules to generate actionable alerts. It's the analytical brain of the SOC: it turns volume into signal.

Full detail in what is SIEM.

SOAR (Security Orchestration, Automation and Response)

Automates the response to alerts through playbooks: enrichment with threat intelligence, initial containment (isolate endpoint, disable account, block IP), notification to stakeholders and ticket orchestration. Reduces L1 repetitive work and lowers MTTR.

XDR (Extended Detection and Response)

Integrated platform that collects its own telemetry from several vectors (endpoint, network, identity, email, cloud), applies detection with the vendor's pre-trained models and allows native response (isolate, contain, kill chain) from the same console. It's the evolution of EDR to a broader scope with less integration work from the client side.

What each does and where the difference sits

The boundary isn't always sharp, but it's worth fixing the underlying logic.

SIEM: the analytical source of truth

A SIEM ingests logs from any source: firewalls, EDR, operating systems, identities (Active Directory, IdP), databases, applications, CloudTrail/Activity Log, SaaS. It normalises, indexes and runs rules the client writes or adapts.

Operational characteristics:

• Deeply customisable: rules reflect each company's context.
• Long history: logs are stored for months or years (typical requirement in NIS2 and other frameworks).
• Ongoing tuning work to reduce false positives.
• Significant maintenance: parsers, agents, capacity, storage costs.

Common platforms: Microsoft Sentinel, Splunk, Elastic Security, Wazuh (open source, covered in Wazuh SIEM), Sumo Logic, IBM QRadar, LogRhythm.

SOAR: response automation

SOAR doesn't detect (or detects little). What it does is act on the alert: enrich, decide and orchestrate actions. A typical SOAR playbook for a credential stuffing alert:

1. Receive the alert from the SIEM or the IdP.
2. Enrich with threat intelligence (does the attacking IP appear in known feeds?).
3. Check the user's historical behaviour.
4. If attack confirmed: disable the account, revoke active sessions, notify the SOC, create a ticket in the ITSM.
5. If ambiguous: send a task to the L2 analyst with all the context gathered.

Operational characteristics:

• Doesn't ingest logs by itself: depends on the SIEM or the platforms that generate alerts.
• Massive integrations with SaaS, IAM, EDR, firewalls, ITSM, communication.
• Reduces manual workload: false positives get filtered automatically, clear attacks get contained without human intervention.

Common platforms: Palo Alto XSOAR (Demisto), Splunk SOAR, Microsoft Sentinel Logic Apps, IBM Resilient, Tines, Torq, Swimlane.

XDR: integrated detection and response with proprietary data

XDR is the most recent model and the one generating the most confusion, because it overlaps partially with SIEM, SOAR and EDR.

The essential difference: XDR collects its own telemetry from endpoint, network, identity and cloud using the vendor's agents and connectors, detects using pre-trained models on that data (not rules you write) and responds in an integrated way from the same console. It works "out of the box" with far fewer manual integrations than a SIEM.

Operational characteristics:

• Fast deployment: the vendor brings the connectors ready.
• Curated detection: the vendor maintains the rules (less tuning, less flexibility).
• Integrated response: isolating endpoints, disabling accounts and blocking attacker infrastructure happen from the platform itself without jumping to external tools.
• Short history and limited depth: doesn't replace SIEM for forensic investigation or long retention.

Common platforms: Microsoft Defender XDR, Palo Alto Cortex XDR, CrowdStrike Falcon XDR, SentinelOne Singularity XDR, Trend Micro Vision One, Trellix XDR.

Quick comparison table

To see it without going into detail:

Does XDR replace SIEM?

Frequent question in RFPs. Short answer: not in medium and large organisations, partially yes in highly standardised SMEs.

Two reasons sustain coexistence:

1. Retention and compliance. Regulations like NIS2, DORA, ENS, PCI or ISO 27001 require long log retention (typically 6 months to several years) across diverse sources. XDRs retain little and only over integrated sources. SIEM remains necessary to cover regulatory scope.
2. Context customisation. A well-written SIEM captures organisation-specific behaviours (authorisations in your internal app, ERP flows, custom integrations) that a vendor XDR doesn't contemplate.

In the real world, the frequent pattern is XDR for fast detection on endpoint/identity/cloud + SIEM for broad correlation, retention and compliance + SOAR cutting across both to automate response. The three coexist and complement each other.

Real use case: detecting ransomware with all three in play

To fix the logic with a concrete scenario.

1. 00:00, initial vector. A user opens a malicious Office document received via email. XDR detects the execution of a winword.exe child process invoking PowerShell with suspicious parameters. Marks the alert as critical.
2. 00:01, immediate block. XDR automatically isolates the endpoint from the network to prevent lateral movement.
3. 00:02, SOAR enrichment. SOAR receives the alert, queries threat intelligence, verifies the user's history, checks if other endpoints opened the same document.
4. 00:03, SIEM correlation. SIEM detects, by adding IdP logs, unusual authentication attempts with the affected user's account from another location. Escalates severity and triggers an additional SOAR playbook.
5. 00:05, coordinated containment. SOAR: disables the user account, revokes sessions, blocks the attacking IP on the firewall, opens a P1 ticket in the ITSM, notifies the SOC.
6. 00:10, human analysis. The L2 analyst has the full chain: XDR alert, correlated SIEM events, SOAR actions already executed. Decides additional actions and closes the incident or escalates to DFIR.

Without XDR, detection would have arrived later. Without SOAR, containment would have depended on a human in working hours. Without SIEM, cross-source correlation would have gone unnoticed. All three contribute something different to the same event.

How to combine them in practice

Three patterns repeat in organisations that get the stack right.

Pattern 1: XDR as endpoint/identity layer + light SIEM

SMEs and mid-sized companies focused on Microsoft 365 + AWS/Azure. They use Microsoft Defender XDR or CrowdStrike Falcon XDR for fast detection on endpoint, identity and cloud, and a light SIEM (Sentinel, Wazuh, Elastic) for retention and correlation with sources the XDR doesn't cover. Light SOAR (Sentinel Logic Apps, Tines) automates recurring actions.

Pattern 2: SIEM as hub + XDR/EDR feeding it

Mid-large companies with many legacy sources and strong compliance requirements. SIEM centralises everything (Splunk, Sentinel at scale), receives alerts from several EDR/XDR and applies its own rules. SOAR runs complex playbooks. XDR contributes its detection but isn't the centre.

Pattern 3: Unified platform from the same vendor

Some vendors offer the full package (Microsoft Sentinel + Defender XDR, Splunk Enterprise Security + SOAR, Palo Alto Cortex XSIAM). Native integration, but strong dependency on the provider. Advantage in simplicity, medium-term risk if the relationship with the vendor changes.

Which to choose by size and maturity

Quick guide to avoid getting the first decision wrong.

Small company without a dedicated team

XDR + managed MDR. XDR covers the essentials with little deployment effort; MDR provides 24x7 coverage and human expertise. A full SIEM isn't justified yet.

Mid-sized SME with a security function

XDR + light SIEM + light SOAR. The combination provides coverage, retention and automation with a team of 2-4 analysts. If regulatory scope grows (NIS2, DORA), SIEM becomes mandatory.

Large company with its own SOC

Full SIEM + mature SOAR + XDR as sensor. The SOC operates the entire ecosystem; the SIEM is the central tool; the XDR feeds detections and allows fast containment.

Critical regulated organisations

Full SIEM, SOAR, XDR and dedicated threat hunting, plus adversary simulation platforms (BAS) to validate continuous coverage against MITRE ATT&CK TTPs.

Common mistakes when deploying SIEM, SOAR or XDR

Patterns that show up in failed projects or those with low ROI.

1. Buying SIEM without a team to write rules. Ends up as an expensive central log tool with no detection value.
2. Buying SOAR without mature SIEM/XDR behind it. SOAR amplifies what sits above it; if what sits above is noise, it automates noise.
3. Expecting XDR to replace SIEM in a regulated organisation. Falls into a retention and compliance gap.
4. Not measuring real metrics (MTTD, MTTR, false positives, ATT&CK coverage). Without metrics, there's no way to know if the investment works.
5. Switching vendors every 2 years without consolidating. Each migration burns months of capacity and loses specific detections that had been written.
6. Outsourcing to MDR without understanding the split. Who writes rules, who tunes them, who owns the data, what SLAs apply and what stays inside or outside scope.

Frequently asked questions

What's the difference between SIEM, SOAR and XDR?

SIEM centralises and correlates logs from across the infrastructure to generate alerts through rules the client customises. SOAR automates response to those alerts with playbooks: enriches, contains, notifies. XDR is a vendor platform that collects its own telemetry across endpoint, identity, network and cloud, detects with pre-trained models and allows native response from the same console. SIEM stands out for customisation and retention; SOAR for automation; XDR for deployment speed and curated detection.

Does XDR replace SIEM?

In medium and large organisations, no. XDRs retain little history, don't cover all sources (especially legacy and non-integrated SaaS) and don't allow the customisation each company's context demands. The norm is for XDR to feed the SIEM or for both to coexist. In SMEs highly standardised on a single vendor (everything Microsoft 365 + Defender XDR, for instance), XDR can cover most of the work, although compliance demands (NIS2, DORA, ISO 27001) end up pushing to add a light SIEM.

Do I need SOAR if I already have SIEM and XDR?

It depends on volume and team size. Not essential if the team manages current volume by hand, but drastically lowers MTTR when alerts grow or when the team is small. The practical rule: if the L1 analyst spends more than 60% of their time on repetitive tasks (enriching alerts, disabling accounts, opening tickets), a light SOAR (Tines, Torq, Logic Apps) has clear return.

How much does a SIEM cost in a mid-sized company?

It depends on the volume of logs ingested per day and the provider. Commercial platforms bill by EPS (events per second) or GB/day. For a mid-sized company, annual cost of the SIEM plus operation lands in high market ranges. Open source alternatives like Wazuh or Elastic reduce licensing but shift the cost to internal operation: someone has to maintain parsers, cluster, integrations and rules.

What's the relationship between XDR and EDR?

EDR (Endpoint Detection and Response) detects and responds on endpoints only. XDR (Extended) broadens scope to other vectors (identity, network, cloud, email) integrated in the same vendor platform. In practice, almost every XDR today was born as EDR and grew. More detail in what is EDR.

Can I have a SOC without SIEM?

Yes, small SOCs operate with XDR + EDR + alerts from critical SaaS and enough human expertise. But as the organisation grows or enters regulatory frameworks, SIEM becomes mandatory for retention, broad correlation and auditable evidence. SOC model detail in what is a SOC.

What metrics should the defensive team measure with these tools?

The five basics: MTTD (mean time to detect), MTTR (mean time to respond), false positive rate, coverage over MITRE ATT&CK and number of own detections created per quarter. Detail in what is Blue Team.

Related resources

• What is SIEM
• What is Wazuh: open source SIEM
• What is EDR
• What is a SOC
• What is Blue Team
• What is MDR
• What is MITRE ATT&CK

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About to invest in SIEM, SOAR or XDR and unsure which fits first? At Secra we review context (team size, regulatory scope, sources already integrated, operating budget) and propose the stack that truly delivers detection and response without ending as an expensive project with no return. Tell us what you have today and we'll see where to start.