SIDE BY SIDE · FACTS ONLY

Defender EASM vs Tenable: asset inventory facts side by side

SHORT ANSWER

Defender EASM describes 2 of the five approaches on the pages we read and Tenable describes 3; they differ on CAASM aggregation and Exposure management. On collection, Defender EASM works without new agents and Tenable does not describe its collection method on the pages we read. Many estates run two of these approaches together, so the question is often which pair, not which one; we do not score either.

By The Inventory Desk · CAASM Finder · Published 2026-10-11

Desk research from public vendor pages read on 27 September and 11 October 2026. Profiles follow our published method; we did not run the products.

How do their approaches compare?

Top bar: Microsoft Defender EASM
Lower bar, lighter: Tenable One

Full bar: described on the vendor's pages we read
Hatched bar: described with a condition (another product, a higher tier, or part of the approach)
Stub: not in our sources (it may exist; we did not find it)

The bars show what each vendor's own pages describe, or how your answers weigh the five approaches. They are not a measure of how well a product works.

What are the facts, side by side?

From each vendor's own pages. Differs marks rows where the recorded status or check value differs.
Fact	Microsoft Defender EASM	Tenable One
Positioning	Microsoft's external attack surface management service, run as an Azure resource, with a prebuilt inventory, recursive discovery from seeds and billing on the Azure bill.	Tenable's exposure management platform. Tenable Attack Surface Management, part of Tenable One, maps external assets from a map of more than 5 billion assets; Tenable One adds attack path analysis, Hexa AI remediation and connectors for third-party data.
Deployment	An Azure resource. Cross-tenant resource access, including Azure Lighthouse, is not supported. Source: Microsoft Learn: Defender EASM overview · Read 27 Sep 2026	Tenable Attack Surface Management is sold through a demo request, not online. Source: Tenable: buy · Read 27 Sep 2026
CAASM aggregationDiffers	Not in our sources Not described on the pages we read.	With a condition Tenable One Connectors bring third-party data into the platform; a unified asset inventory is not described in detail on the pages we read. Source: Tenable One · Read 27 Sep 2026
Agent-based inventory	Not in our sources Not described on the pages we read.	Not in our sources Not described on the pages we read.
External attack surface management	Described A prebuilt inventory for many organisations plus recursive discovery from seeds you supply. Source: Microsoft Learn: what is discovery · Read 27 Sep 2026	Described Identifies domains related to your inventory from a map of 5 billion+ assets with 200+ metadata fields. Source: Tenable Attack Surface Management · Read 27 Sep 2026
CMDB-centred inventory	Not in our sources Not described on the pages we read.	Not in our sources Not described on the pages we read.
Exposure managementDiffers	With a condition Dashboards for vulnerabilities, compliance and hygiene on external assets; remediation happens downstream through Log Analytics and Azure Data Explorer. Source: Microsoft Learn: data connections · Read 27 Sep 2026	Described Tenable One is Tenable's exposure management platform, with attack path analysis across 150+ techniques and Hexa AI automated remediation. Source: Tenable One · Read 27 Sep 2026
Servers and network devicesDiffers	Not in our sources	Partly Tenable One includes vulnerability management alongside external attack surface data. Source: Tenable: buy · Read 27 Sep 2026
Cloud workloads	Not in our sources	Not in our sources
SaaS applications	Not in our sources	Not in our sources
Identities as assets	Not in our sources	Not in our sources
Off-network laptops	Not in our sources	Not in our sources
OT and IoT devices	Not in our sources	Not in our sources
Internet-facing discovery	Matches Prebuilt inventory and recursive discovery from seeds. Source: Microsoft Learn: what is discovery · Read 27 Sep 2026	Matches A 5 billion+ asset map with 200+ metadata fields. Source: Tenable Attack Surface Management · Read 27 Sep 2026
Offers its own agent	Not in our sources	Not in our sources
Works without new agentsDiffers	Matches An Azure service that discovers from seeds and a prebuilt inventory. Source: Microsoft Learn: Defender EASM overview · Read 27 Sep 2026	Not in our sources
Merges records from several sourcesDiffers	Not in our sources	Partly Tenable One Connectors bring third-party data into the platform. Source: Tenable One · Read 27 Sep 2026
Feeds or updates a CMDB	Not in our sources	Not in our sources
Cross-source queries and reportsDiffers	Partly Dashboards for vulnerabilities, compliance and hygiene. Source: Microsoft Learn: Defender EASM overview · Read 27 Sep 2026	Not in our sources
Workflows, tickets or actions	Partly Data connections to Log Analytics and Azure Data Explorer trigger remediation actions downstream. Source: Microsoft Learn: data connections · Read 27 Sep 2026	Partly Hexa AI orchestrates automated remediation in Tenable One. Source: Tenable One · Read 27 Sep 2026
Price or pricing basis published	Partly Billable assets are defined (approved host:IP combinations, domains and IP addresses) and charged on the Azure bill; Microsoft's pricing page showed no rate when we read it. Source: Microsoft Learn: understanding billable assets · Read 27 Sep 2026	Partly Attack Surface Management is not sold online; Tenable publishes adjacent prices, such as Tenable One Vulnerability Management at $3,700 for one year for up to 250 assets. Source: Tenable: buy · Read 27 Sep 2026
Free tier or trialDiffers	Matches A 30-day free trial, then Azure billing. Source: Microsoft Learn: understanding billable assets · Read 27 Sep 2026	Partly Free trials for Tenable One Vulnerability Management and Nessus; the Tenable One platform and its exposure products are demo only. Source: Tenable free trials · Read 11 Oct 2026
Platform it is part of	Microsoft: Native to Azure, billed on the Azure bill, with a Security Copilot integration in preview. Source: Microsoft Learn: Defender EASM documentation · Read 27 Sep 2026	Tenable: External findings sit in Tenable One next to Tenable vulnerability data. Source: Tenable One · Read 27 Sep 2026
Integrations	Data connections to Log Analytics and Azure Data Explorer, and a Security Copilot integration in preview. Source: Microsoft Learn: data connections · Read 27 Sep 2026	Tenable One Connectors bring third-party data into the platform. Source: Tenable One · Read 27 Sep 2026
Price	Billed through Azure on billable assets (approved host:IP combinations, domains and IP addresses) after a 30-day free trial. Microsoft's pricing page did not show a rate when we read it; check it for the current figure. Source: Microsoft Learn: understanding billable assets · Read 27 Sep 2026	Attack Surface Management: demo request only. Adjacent published price: Tenable One Vulnerability Management at $3,700 for one year for up to 250 assets. Source: Tenable: buy · Read 27 Sep 2026

Where do they differ?

CAASM aggregation: Defender EASM is not in our sources; Tenable describes it with a condition.
Exposure management: Defender EASM describes it with a condition; Tenable describes it.
Servers and network devices: Defender EASM is not in our sources; Tenable partly matches.
Works without new agents: Defender EASM matches; Tenable is not in our sources.
Merges records from several sources: Defender EASM is not in our sources; Tenable partly matches.
Cross-source queries and reports: Defender EASM partly matches; Tenable is not in our sources.
Free tier or trial: Defender EASM matches; Tenable partly matches.

Can they work together?

Neither vendor's pages we read name the other as an integration. That does not mean they cannot work together; ask both vendors.

Choose Defender EASM if

You are on Azure and want an external inventory without a sales call
You want an outside-in baseline before choosing an inventory platform

Choose Tenable if

You already run Tenable vulnerability management
Your question is which exposures to fix first more than which assets exist

Which limits should you check?

Defender EASM

External assets only: internal devices, SaaS apps and identities are not covered.
No built-in remediation workflow, and no cross-tenant resource access for groups with several Azure tenants.

Tenable

Attack Surface Management and the Tenable One platform are demo only; free trials cover Vulnerability Management and Nessus.
A unified internal asset inventory, SaaS apps and identities are not described on the pages we read.

Put Defender EASM and Tenable in the asset census with others Run the finder

Questions people ask

Is Defender EASM or Tenable better?

Neither is scored on this site. Defender EASM describes 2 of five approaches and Tenable 3 on the pages we read, and they differ on 7 recorded facts. Which fits depends on where your assets live, whether you can install agents, your CMDB and your tools; the finder checks those.

Do Defender EASM and Tenable work with a CMDB?

Defender EASM: Not in our sources. Tenable: Not in our sources.

Do Defender EASM or Tenable publish prices?

Defender EASM: Billed through Azure on billable assets (approved host:IP combinations, domains and IP addresses) after a 30-day free trial. Microsoft's pricing page did not show a rate when we read it; check it for the current figure. Tenable: Attack Surface Management: demo request only. Adjacent published price: Tenable One Vulnerability Management at $3,700 for one year for up to 250 assets.