12 Best Attack Surface Management (ASM and EASM) Tools for 2026

Attack surface management (ASM) is the continuous discovery, inventory and risk assessment of every asset an attacker could target. That includes the internet-facing domains, IP addresses, cloud services, APIs, certificates and forgotten test servers you know about, and the ones you don’t. ASM tools look at your organisation from the outside, the way an attacker would, then flag exposures such as open ports, outdated software and misconfigured cloud storage before someone else finds them.

The category has grown because attack surfaces now change daily. Every new SaaS tool, cloud project, acquisition and marketing microsite adds assets, often without IT knowing. The tools below differ in how they discover those assets, whether they actively test them, and whether they also look inside your network.

ASM vs EASM vs CAASM

How we evaluated these tools

Attack surface management tools at a glance

12 best ASM tools reviewed

1. Microsoft Defender External Attack Surface Management

Best for: organisations heavily invested in Microsoft security and Azure.

Defender EASM starts from “discovery seeds” you provide, such as domains and IP blocks, and recursively finds connected domains, hosts, IP ranges, ASNs and Whois records. Assets are classified as current or historic, and dashboards highlight vulnerabilities, compliance issues and hygiene problems. Customer data is stored in the Azure region you choose.

Key features

• Seed-based recursive discovery
• Inventory of domains, hosts, IP blocks and certificates
• Vulnerability and hygiene dashboards
• Integration with Microsoft Sentinel and Defender

Deployment: Azure service; data stored in your selected region.

Pricing: on request 

Pros

• Natural fit for Microsoft security stacks
• Choice of data region

Cons

• Strongest value inside Azure and Microsoft environments
• Discovery quality depends on good seeds

Not for: organisations outside the Microsoft security ecosystem.

2. Palo Alto Networks Cortex Xpanse

Best for: large enterprises and government bodies with sprawling, global internet footprints.

Cortex Xpanse scans the entire IPv4 internet continuously and attributes discovered assets to your organisation, including those from subsidiaries and acquisitions. It can automatically remediate common exposures through playbooks. Palo Alto has also added exposure management capabilities to its Cortex platform, so check how Xpanse is packaged for you.

Key features

• Internet-wide scanning and asset attribution
• Automated remediation playbooks
• Integration with Cortex XSOAR and XSIAM
• Coverage of cloud and on-premise internet-facing assets

Deployment: SaaS.

Pricing: on request.

Pros

• Very broad internet visibility
• Strong automation

Cons

• Premium pricing
• Best value inside the Palo Alto ecosystem

Not for: small and mid-size organisations.

3. CrowdStrike Falcon Exposure Management

Best for: CrowdStrike customers who want internal and external exposure in one console.

Falcon Exposure Management combines external attack surface management with internal asset discovery through the Falcon agent. It brings in active and passive discovery and API data from tools such as ServiceNow and Active Directory, and maps attack paths across endpoints, cloud and identities. Findings are prioritised with CrowdStrike’s ExPRT.AI model.

Key features

• EASM plus internal discovery through the Falcon sensor
• Attack path mapping
• ExPRT.AI prioritisation
• Automated workflows with Falcon Fusion

Deployment: cloud (Falcon platform).

Pricing: on request.

Pros

• Inside and outside view in one place
• Strong threat intelligence

Cons

• Most valuable with Falcon deployed widely
• Pricing not published

4. Tenable Attack Surface Management

Best for: Tenable customers who want external exposure joined with internal vulnerability data.

Tenable ASM discovers internet-facing assets from your domains and maps them in detail, with hundreds of data fields per asset. As part of the Tenable One platform, it combines external findings with internal vulnerability, cloud and identity data, so you can see how an exposed asset connects to risk inside.

Key features

• Seed-based external discovery
• Detailed asset fingerprinting
• Integration with Tenable One exposure management
• Change tracking over time

Deployment: cloud.

Pricing: on request.

Pros

• Joins external and internal risk
• Mature vendor

Cons

• Strongest within the Tenable platform
• Discovery depends on seed quality

Not for: teams that want a standalone, low-cost EASM tool.

5. Rapid7 Surface Command

Best for: teams that want one view of internal and external assets built from the tools they already own.

Surface Command combines external scanning with internal asset data pulled from more than 150 integrations, including endpoint management, endpoint security, cloud security and CMDB tools. It correlates everything into one inventory, highlights gaps such as devices missing an EDR agent, and tracks fixes with owners and SLAs. It also forms part of Rapid7’s Exposure Command platform.

Key features

• Internal and external asset correlation (CAASM)
• More than 150 tool integrations
• Coverage-gap detection
• Remediation tracking and automation

Deployment: cloud.

Pricing: on request.

Pros

• Uses data you already have
• Finds security-control gaps, not just exposed assets

Cons

• Value depends on how many tools you connect
• Packaging overlaps with Exposure Command

Not for: organisations with very few existing security tools.

6. Censys

Best for: security teams that want deep internet-wide data for discovery and threat hunting.

Censys maintains one of the largest continuously updated maps of internet hosts, services and certificates. Its attack surface product uses that data to find and track assets that belong to you, and threat hunters use the same data to investigate attacker infrastructure.

Key features

• Internet-wide host and certificate data
• Asset discovery and change tracking
• Search for threat hunting and research
• API access

Deployment: cloud.

Pricing: on request [VERIFY current packaging].

Pros

• Excellent data quality and coverage
• Useful beyond ASM for threat research

Cons

• Mostly passive; does not validate exploitability
• Product packaging has changed over time

7. CyCognito

Best for: large organisations with many subsidiaries, brands and acquisitions.

CyCognito discovers assets by mapping your business structure, then runs automated security testing across them. Its testing engines apply more than 100,000 tests in over 30 categories. GigaOm named it a Leader in its 2026 Radar for Attack Surface Management, for the third year running.

Key features

• Business-structure-led discovery of unknown assets
• Automated, payload-based security testing
• Prioritisation by business context
• Integrations with Armis, Axonius, Wiz and ServiceNow

Deployment: SaaS.

Pricing: on request.

Pros

• Strong at finding assets you did not know you had
• Active validation reduces false positives

Cons

• Algorithmic ownership attribution needs review
• Enterprise pricing

Not for: small organisations with a simple footprint.

8. Bitsight

Best for: organisations that want exposure data alongside security ratings and third-party risk.

Bitsight is best known for security ratings, which score organisations based on their external security posture. Its external attack surface management product uses the same internet-wide data to show your own exposed assets. The combination is useful when the same team manages both your exposure and your suppliers’ risk.

Key features

• External asset discovery and exposure findings
• Security ratings for your organisation and vendors
• Benchmarking against peers
• Board-level reporting

Deployment: cloud.

Pricing: on request.

Pros

• Links exposure to third-party risk programmes
• Strong executive reporting

Cons

• Passive data; limited active testing
• Ratings methodology may be questioned by vendors

Not for: teams that want deep technical validation.

9. Mandiant Attack Surface Management (Google Cloud)

Best for: organisations that want intelligence-led checks from frontline incident responders.

Mandiant ASM, sold by Google Cloud, discovers internet-facing assets from simple starting points, such as a domain, IP address or netblock, and connects to cloud and DNS providers. It runs active and passive checks, including benign payloads built from Mandiant’s frontline intelligence, to confirm whether assets are actually exploitable. Role-based access lets subsidiaries manage their own surface while the parent keeps central visibility.

Key features

• Discovery from simple seeds plus cloud and DNS integrations
• Intelligence-informed active checks
• Daily, weekly or on-demand scanning
• Integrations with Google SecOps, Splunk, Cortex XSOAR and ServiceNow

Deployment: SaaS (Google Cloud).

Pricing: tailored enterprise pricing based on the number of employees, with a base fee.

Pros

• Checks informed by real incident response
• Good model for groups with subsidiaries

Cons

• Pricing not published
• Best value alongside Google’s security tools

Not for: small teams on a tight budget.

10. Detectify

Best for: organisations whose attack surface is mostly websites and web applications.

Detectify combines continuous surface monitoring of internet-facing assets with dynamic application security testing (DAST). Its payloads draw on a community of ethical hackers, so it is strong at catching web vulnerabilities and misconfigurations as they emerge.

Key features

• Continuous discovery of domains and subdomains
• Web vulnerability testing informed by ethical hackers
• Application and API scanning
• Integrations with ticketing and chat tools

Deployment: SaaS.

Pricing: an independent review lists Surface Monitoring from about $302 a month for 25 assets, and Application Scanning from about $90 a month. Enterprise is quoted.

Pros

• Strong web vulnerability coverage
• Published starting prices

Cons

• Less suited to non-web infrastructure
• Per-asset costs grow with large footprints

Not for: organisations with mostly non-web exposure.

11. Attaxion

Best for: mid-size organisations that want EASM with transparent pricing.

Attaxion discovers internet-facing assets, maps their relationships and flags exposures, with agentless traffic monitoring and prioritised findings. It is one of the few ASM vendors to publish its prices.

Key features

• Continuous external asset discovery
• Vulnerability and exposure detection
• Asset relationship mapping
• Prioritised remediation guidance

Deployment: SaaS.

Pricing: listed at $129 a month for 40 assets (Starter), $349 for 120 (Plus) and $949 for 360 (Business); Enterprise is quoted. Free trial.

Pros

• Clear published pricing
• Quick to start

Cons

• Smaller vendor
• Fewer integrations than the enterprise platforms

Not for: large global groups with thousands of assets.

12. runZero

Best for: finding every device on your networks, including unmanaged, IoT and OT equipment.

runZero uses safe active scanning and passive discovery to fingerprint devices in detail, internal and external, without credentials. It also connects to EDR, cloud and MDM tools to highlight devices that are missing controls. It is one of the few tools in this list that can run with a self-hosted console.

Key features

• Unauthenticated active and passive discovery
• Detailed fingerprinting of IT, IoT and OT devices
• Integrations to find coverage gaps
• External attack surface discovery [VERIFY edition]

Deployment: cloud, or a self-hosted console with a Platform licence and support package.

Pricing: free Community Edition for up to 100 assets; Platform from $5,000. 21-day trial.

Pros

• Exceptional internal device discovery
• Self-hosted console option

Cons

• External ASM is not its main focus
• Community Edition is limited

Not for: teams that only want an external view.

Your collaboration stack is part of your attack surface

Every SaaS collaboration tool adds to the surface an attacker can see. It brings its own login pages, single sign-on endpoints, OAuth integrations, public file-sharing links, guest accounts and API tokens. Attackers increasingly target these instead of your perimeter, because a compromised chat or file-sharing account gives them access to internal conversations, documents and people.

When you run an ASM tool, look specifically for:

• Public sharing links to internal files and channels
  
• Third-party apps and bots with broad permissions in chat workspaces
  
• Guest and external accounts that were never removed
  
• Forgotten workspaces created by individual teams
  
• Webhooks and API tokens exposed in code or documentation
  

Reducing exposure by bringing critical SaaS in-house

ASM tells you what is exposed. The next question is whether those services need to be on the public internet at all. For most organisations, a few systems carry most of the risk: internal communication, file sharing and identity. Moving those to infrastructure you control removes whole categories of internet-facing assets from your attack surface.

That is why defence, intelligence and government organisations often self-host internal messaging. A platform such as Troop Messenger, deployed on-premise, can run entirely inside your network or in an air-gapped environment, with no public login page, no third-party OAuth apps and no external tenant for attackers to find. ASM tools then have less to report, which is the best result there is.

How to choose an ASM tool

• Decide your scope: external only (EASM), internal inventory (CAASM), or both.
  
• Test discovery on your real footprint, including subsidiaries and acquisitions, and compare what each tool finds.
  
• Check ownership accuracy. False attribution creates noise and wasted effort.
  
• Ask how exposures are validated: passive data, safe active checks or payload-based testing.
  
• Confirm integrations with your vulnerability, SIEM, SOAR and ticketing tools.
  
• Review data handling. Where are findings about your exposures stored?
  
• Understand the pricing unit: assets, employees, domains or IP ranges.
  
• Run a proof of value of at least 30 days to see how much the tool finds that you did not know about.
  

Frequently asked questions

1. What is an attack surface management tool?

An attack surface management tool continuously discovers the assets an attacker could target, such as domains, IP addresses, cloud services, APIs and certificates, then checks them for exposures like open ports, outdated software and misconfigurations. It gives security teams an outside-in view of their organisation and alerts them when new risks appear.

2. What is the difference between attack surface management and vulnerability management?

Attack surface management finds and inventories what you have, especially internet-facing assets you may not know about. Vulnerability management assesses known assets in depth for software flaws and tracks fixes. ASM answers “what is out there?”, while vulnerability management answers “what is wrong with it?”. Most programmes need both.

3. What is EASM?

EASM stands for external attack surface management. It focuses on internet-facing assets, scanning from the outside the way an attacker would to find domains, subdomains, IP addresses, cloud services and exposed applications that belong to your organisation, including ones IT does not know about.

4. How often should you scan your attack surface?

Continuously, or at least daily. Attack surfaces change every time a team launches a cloud service, website or SaaS tool. Most ASM tools rescan automatically and alert you to new assets and exposures. Weekly or monthly scans leave long windows in which attackers can find something before you do.

5. Does attack surface management replace penetration testing?

No. ASM provides continuous, broad discovery and automated checks across your whole footprint. Penetration testing is a deeper, human-led exercise on selected targets that can chain weaknesses together. The two complement each other: ASM finds what to test, and penetration testing proves how far an attacker could get.