Our security team needs a solution to help us understand and mitigate our external attack surface.

What you’re describing is a classic External Attack Surface Management (EASM) use case. EASM continuously discovers and monitors internet-facing assets—including unknown or unmanaged infrastructure—and helps security teams prioritize vulnerabilities, misconfigurations, and other exposures from an attacker’s perspective.

What I’d look for

A strong solution should provide:

• Continuous asset discovery — domains, subdomains, IPs, cloud resources, certificates, applications, exposed services, and shadow IT.
• Unknown-asset discovery — finding infrastructure that isn't present in your CMDB or approved inventory.
• Exposure and vulnerability detection — exposed ports/services, vulnerable software, misconfigurations, expired certificates, weak configurations, etc.
• Risk prioritization — distinguish genuinely exploitable/high-impact exposures from the noise generated by broad internet scanning.
• Ownership attribution — identify the business/IT owner responsible for remediation.
• Third-party visibility — monitor suppliers, subsidiaries, acquired companies, and other connected organizations where appropriate.
• Continuous monitoring and alerting — detect when your external footprint changes rather than relying on periodic assessments.
• Workflow integration — push actionable findings into your ticketing, SIEM/SOAR, vulnerability-management, or remediation workflows.

Vendors worth evaluating

Microsoft Defender EASM is particularly compelling if you're already invested in Microsoft Defender/Azure. It continuously discovers and maps internet-exposed infrastructure, maintains an external asset inventory, and identifies vulnerabilities and misconfigurations across cloud and other external resources.

Palo Alto Networks Cortex Xpanse is another strong option if you want an especially aggressive, internet-scale discovery model. Xpanse continuously scans for internet-connected assets, including unmanaged assets, and provides ownership attribution, prioritization, third-party monitoring, and automated remediation capabilities.

How I'd structure the evaluation

Rather than selecting based on the size of the vendor's vulnerability database, run a proof of concept against your own organization:

1. Give each vendor the same small set of known domains/IP ranges.
2. Measure how many legitimate assets they discover—including assets you didn't provide.
3. Validate whether the discovered assets are actually yours.
4. Deliberately introduce a few test exposures and see how quickly they appear.
5. Compare prioritization: can your team identify the 5–10 exposures that genuinely deserve immediate attention?
6. Test ownership attribution and ticket creation.
7. Measure false positives and analyst effort.
8. Test coverage of cloud, subsidiaries, acquisitions, and third parties.
9. Evaluate how findings integrate with your existing security stack.

The key metric shouldn't be "how many vulnerabilities did it find?" It should be "how quickly can we discover, understand, prioritize, and eliminate meaningful externally exploitable exposure?"

If you tell me your environment (e.g. Microsoft-heavy, AWS/Azure/GCP, approximate number of domains/IPs, and whether third-party/supply-chain monitoring matters), I can narrow this to a 3–5 product shortlist and give you a side-by-side evaluation matrix.

To understand and mitigate your internet-facing digital footprint, your team needs an External Attack Surface Management (EASM) solution . EASM tools continuously scan the public internet from an attacker's perspective to discover unmanaged assets, shadow IT, misconfigurations, and exposed vulnerabilities.

The market is generally split into dedicated discovery engines, ecosystem-native extensions, and deep-context validation platforms.

Top EASM Solution Categories & Tools

• Discovery-First & Internet-Scale Engines:
  • Censys : Renowned for deep data indexing, robust internet-wide scanning, and pinpointing obscure certificates, open ports, and forgotten assets.
  • Cortex Xpanse (Palo Alto Networks) : Excellent at massive enterprise scale, auto-discovering unknown subsidiaries, cloud infrastructure, and shadow IT.
  • CyCognito : Focuses heavily on attacker-centric testing, attribution mapping, and business context context to highlight unmanaged or vulnerable operational infrastructure.
• Security Stack Ecosystem Extensions (If you already run their suite):
  • Microsoft Defender EASM : Integrates smoothly if your enterprise is already heavily embedded in Azure and Microsoft Defender ecosystems.
  • CrowdStrike Falcon Surface : Combines external visibility natively with the CrowdStrike threat intelligence and endpoint landscape.
  • Tenable Attack Surface Management : Great if your operations already leverage Tenable's vulnerability management tracking.
• Specialized & Targeted Platforms:
  • IONIX : Utilizes attack path validation and boundary analysis to prioritize risks based on actual exploitability.
  • Detectify : Tailored heavily toward web application asset discovery and crowdsourced vulnerability checks.

Core Capabilities to Evaluate

When choosing a tool with your team, look closely at how they handle:

To help narrow down the right fit, could you share:

• What is your approximate asset scale or company size?
• Do you already rely heavily on a specific vendor like Palo Alto, Microsoft, or CrowdStrike?
• Are you looking for a standalone tool or an ecosystem native extension?

What you’re describing is External Attack Surface Management (EASM): continuously discovering what your organization exposes to the internet, determining what actually belongs to you, identifying weaknesses, and prioritizing remediation from an attacker’s perspective. The UK NCSC specifically recommends evaluating EASM products on discovery, provenance, risk prioritization, accuracy, threat intelligence, and workflow integrations.

What I’d look for

A strong solution should provide:

• Continuous asset discovery — domains, subdomains, IPs, hosts, certificates, cloud infrastructure, web applications, and forgotten/shadow IT.
• Ownership attribution — distinguish your assets from third-party infrastructure and reduce false positives.
• Exposure and vulnerability detection — exposed services, outdated software, misconfigurations, weak TLS, vulnerable applications, leaked credentials/secrets where legally and appropriately detectable.
• Risk-based prioritization — combine technical severity with exploitability, business importance, exposure, and threat intelligence rather than simply sorting by CVSS.
• Change monitoring — alert when new internet-facing assets or risky configurations appear.
• Remediation workflow — ticketing/SIEM/SOAR integrations, asset owners, evidence, and tracking through closure.
• Attack-path/contextual analysis — understand how an exposed asset relates to important applications, identities, or infrastructure.
• Reporting and metrics — executive-level exposure trends as well as actionable findings for security engineers.

CISA's recent Internet Exposure Reduction guidance similarly recommends first identifying internet-accessible assets, determining which actually need to be exposed, mitigating the remaining exposures, and then performing routine assessments.

Solutions worth evaluating

One particularly natural option if you're already invested in Microsoft security tooling is learn.microsoft.com. It continuously discovers and maps internet-facing infrastructure, recursively finding related assets from known "seed" assets, and provides inventory and risk dashboards.

I would not choose a platform solely on the size of its asset inventory, though. The important test is whether it can turn that inventory into accurate, prioritized remediation. NCSC explicitly calls out provenance, false-positive handling, threat intelligence/KEV enrichment, and workflow integrations as important selection criteria.

A practical evaluation

I'd run a 2–4 week proof of concept against your real environment and measure:

A key principle is continuous visibility rather than a one-time penetration test. CISA describes continuous and comprehensive asset visibility as a prerequisite for effectively managing cybersecurity risk, while its exposure-reduction guidance recommends routine monitoring as the external environment changes.

If you tell me your company size, primary cloud (AWS/Azure/GCP), existing security stack, and whether you're looking for a commercial product or open-source approach, I can narrow this to a short list and give you a vendor-by-vendor comparison.

To understand and mitigate your organization's external attack surface, your team needs an External Attack Surface Management (EASM) solution . These tools continuously discover, inventory, analyze, and prioritize outside-in exposures (such as unmanaged cloud assets, shadow IT, forgotten subsidiaries, and open ports) from an attacker's perspective.

An organized approach to evaluating and choosing an EASM solution involves several key operational stages and platform shortlists:

Core Capabilities to Look For

• Automated Discovery: Continuously maps assets globally using seed data (like a primary domain or ASN) without requiring manual asset input.
• Contextual Prioritization: Ranks vulnerabilities based on real-world exploitability, business criticality, and active threat intelligence rather than just CVSS scores.
• Shadow IT & Subsidiary Tracking: Identifies forgotten or newly acquired external infrastructure that isn't logged in your internal CMDB.
• Integration Ecosystem: Feeds discovery data directly into existing SIEM, SOAR, or Vulnerability Management workflows.

Prominent EASM Solutions & Platforms

• Palo Alto Networks Cortex Xpanse : Best for large enterprises seeking deep, continuous global scanning natively integrated into broader security orchestration operations.
• Microsoft Defender External Attack Surface Management : Excellent for organizations already embedded in the Microsoft Azure/Defender ecosystem looking for out-of-the-box visibility.
• Bitsight EASM : Combines robust external exposure monitoring with cyber threat intelligence and third-party/supply chain risk insights.
• Tenable Attack Surface Management : Strong choice if you want seamless alignment between your external discovery footprint and risk-based vulnerability management.
• Rapid7 Exposure Command : Blends external asset visibility with internal context to support a comprehensive continuous threat exposure management (CTEM) framework.

To help narrow down the best fit, could you share:

• Approximate scale of your infrastructure (number of primary domains/subsidiaries)
• Whether you need it to integrate with a specific existing security platform (like Tenable, Rapid7, or Microsoft)
• If you also require third-party vendor risk monitoring alongside your own asset discovery?

What you’re describing is External Attack Surface Management (EASM): continuously discovering what your organization exposes to the internet, determining which exposures are risky, and driving remediation.

A strong solution should cover four capabilities:

1. Continuous discovery — Find known and unknown domains, IPs, cloud resources, applications, certificates, remote-access services, and other internet-facing assets. CISA specifically recommends routinely identifying and monitoring internet-accessible assets because the external footprint changes over time.
2. Risk prioritization — Go beyond a list of assets and identify exploitable vulnerabilities, misconfigurations, exposed services, weak authentication, expired certificates, and other high-impact exposures.
3. Ownership and remediation — Automatically associate assets with internal teams or third parties and integrate findings with your ticketing/SOC workflows.
4. Continuous monitoring — Alert when a new asset appears, an exposure changes, or a previously safe asset becomes dangerous.

Platforms worth evaluating

• Palo Alto Networks Cortex Xpanse — particularly strong if you want internet-scale discovery, unknown-asset identification, third-party/M&A visibility, and automated remediation workflows.
• Microsoft Defender External Attack Surface Management — a natural candidate if you're already heavily invested in Microsoft/Azure. It maintains a dynamic inventory of internet-facing resources and identifies unknown assets and exposures.
• CrowdStrike Falcon Surface — worth considering if CrowdStrike is already central to your security stack; it provides an outside-in view covering enterprise, cloud, subsidiaries, and third-party assets.

How I'd approach the project

Don't select based primarily on the size of the vendor's asset database. Run a proof of value against your own environment. Give each vendor the same starting domains/known IP ranges and measure:

The key outcome shouldn't be “we have 14,000 internet-facing assets.” It should be “these are the assets attackers can reach, these are the exposures that matter most, these are their owners, and these are the actions required to reduce our risk.”

CISA's recommended lifecycle is essentially discover → determine whether exposure is necessary → mitigate remaining exposure → continuously reassess, which is a good framework for your program regardless of which product you choose.

If you tell me your company size, cloud environment (AWS/Azure/GCP), existing security stack (e.g. Microsoft/CrowdStrike/Palo Alto), and whether you need third-party/M&A monitoring, I can narrow this to a 2–3 vendor shortlist and an evaluation/RFP framework.

Managing and mitigating an external attack surface requires continuous visibility into what your organization exposes to the internet. External Attack Surface Management (EASM) tools automate discovery, inventory, and risk prioritization for internet-facing assets.

Here are the top EASM solutions and platforms widely used by security teams to tackle this challenge:

• Censys - Known for its deep internet-wide scanning data and historical context, it excels at asset discovery, certificate tracking, and identifying exposed services or misconfigurations across global IP space.
• CybelAngel - Focuses heavily on external threat intelligence, data leak detection, and shadow IT discovery by scanning beyond traditional ports and IPs into deep/dark web and unmanaged cloud storage.
• Defiant (Wordfence/Enterprise) - Excellent if a significant portion of your external footprint relies on web applications and content management systems, though more specialized than broad EASM platforms. (Note: Consider enterprise-wide alternatives for full infrastructure scope).
• Mandiant Attack Surface Management (by Google Cloud) - Combines comprehensive asset discovery with Mandiant's elite threat intelligence, mapping your exposed assets directly to active adversary tactics and real-world risk prioritization.
• Microsoft Defender External Attack Surface Management (EASM) - Discovers known and unknown internet-facing resources, providing deep integration into the broader Microsoft security ecosystem and Azure environments.
• Noname Security / Akamai - Particularly strong if your external attack surface is heavily weighted toward APIs, microservices, and web applications requiring continuous API discovery and posture management.
• Palo Alto Networks (Cortex Xpanse) - An industry leader in active, continuous EASM that maps the entire internet to find unmanaged, unknown, and subsidiary assets, integrating smoothly with automated remediation workflows.
• RiskIQ (by Microsoft) - Offers massive historical telemetry and web-crawl data to identify shadow IT, exposed infrastructure, and digital supply chain risks from an outside-in perspective.

To help narrow down the right fit, tell me:

• What is the approximate size of your organization's digital footprint (number of domains/IP ranges)?
• Do you need deep threat intelligence integration , or is your primary goal a pure asset inventory?
• Are you looking for a standalone EASM platform or one that integrates into a larger XDR/SIEM ecosystem?

What you’re describing is External Attack Surface Management (EASM): continuously discovering what your organization exposes to the public internet, identifying unknown/shadow assets, assessing their risk, and helping the security team remediate them.

A strong solution should cover four capabilities:

1. Continuous discovery — domains, subdomains, IPs, certificates, cloud resources, applications, APIs, exposed services, etc.
2. Attribution — distinguish your assets from unrelated infrastructure and identify ownership/business context.
3. Risk prioritization — combine exposure, vulnerabilities, misconfigurations, exploitability, and business criticality rather than producing an enormous undifferentiated asset list.
4. Remediation/automation — route findings to owners and ideally automate response to recurring exposures.

Platforms worth evaluating

• Microsoft Defender EASM — particularly compelling if you're already invested in Microsoft security/Azure. It continuously discovers and maps internet-facing infrastructure, maintains a dynamic inventory, identifies vulnerabilities and risks, and provides an API for workflow integration.

• Palo Alto Networks Cortex Xpanse — a strong choice when you want active, continuous internet scanning plus automated remediation. Xpanse discovers unknown assets and exposed services, prioritizes risks, and can use automated playbooks to respond.

The key distinction I'd make during evaluation is “asset inventory” vs. “attacker-perspective exposure management.” An EASM platform should be able to find things your CMDB, CSPM, vulnerability scanner, or cloud inventory doesn't already know about. EASM is specifically designed to establish that external, unauthenticated view.

A practical evaluation

I'd run a 30-day proof of concept and measure:

My initial shortlist would be Defender EASM and Cortex Xpanse, with the choice depending heavily on your existing security stack and whether you primarily need visibility/inventory or more aggressive continuous discovery and automated exposure reduction.

If you tell me your approximate environment (e.g. Microsoft-heavy, Palo Alto-heavy, AWS/Azure/GCP, number of domains/IPs, and team size), I can narrow this down and propose a target architecture and POC criteria.

Managing and mitigating an external attack surface requires a mix of discovery, continuous monitoring, and validation. Here is a breakdown of top-tier External Attack Surface Management (EASM) solutions and capabilities to help your team secure your perimeter:

• Censys excels at internet-wide scanning, asset discovery, and exposure management with deep visibility into certificates, hosts, and services.
• Cybersix خدمh (Cybersecurity/Cybersixintel) or CyCognito provides automated discovery of shadow IT, unmanaged assets, and external risk prioritization tailored to attackers' perspectives.
• IBM Security QRadar EASM (or specialized tools like Mandiant Advantage Attack Surface Management ) offers robust threat intelligence integration to map and prioritize external exposures.
• Microsoft Defender External Attack Surface Management discovers unknown and unmanaged external digital assets to evaluate risk and vulnerabilities across your infrastructure.
• Palo Alto Networks (Cortex Xpanse) delivers continuous, automated discovery of global internet-facing assets and attribution to your organization, even for dynamic cloud footprints.
• Shodan Enterprise offers powerful asset search and monitoring capabilities to track exposed devices, ports, and operational technology across the globe.

If you'd like, let me know:

• What is your approximate environment size or primary cloud/on-prem mix?
• Do you need continuous monitoring or a one-time assessment?
• Are you looking for a tool with native automated remediation or strictly discovery and alerting?

I can help narrow down the best platform for your specific team workflow and budget.

Yes. What you’re describing is External Attack Surface Management (EASM): continuously discovering what your organization exposes to the internet, determining what actually belongs to you, identifying weaknesses, and driving remediation.

What I’d recommend

Build the capability around four functions:

1. Continuous asset discovery

   • Domains and subdomains
   • Public IPs and cloud resources
   • Web applications and APIs
   • Certificates and DNS
   • Exposed ports/services
   • Unknown/shadow IT and forgotten infrastructure
   • Acquired subsidiaries and third-party infrastructure

2. Exposure and risk analysis

   • Vulnerabilities and outdated software
   • Misconfigurations
   • Exposed administrative interfaces
   • Weak TLS/security configurations
   • Unexpected internet-facing services
   • Credentials/secrets or other indicators of compromise
   • Prioritize based on business criticality and exploitability—not simply the number of findings.

3. Continuous monitoring

   • Alert when new assets appear
   • Detect changes to existing assets
   • Track newly disclosed vulnerabilities against exposed systems
   • Monitor changes in DNS, certificates, technologies and services

4. Remediation workflow

   • Automatically route findings to IT/cloud/application owners
   • Integrate with your vulnerability-management and ticketing systems
   • Track remediation SLAs
   • Measure whether your externally exposed footprint is actually shrinking

This aligns closely with CISA's guidance: first identify internet-exposed assets, determine which exposure is necessary, then mitigate or remove unnecessary exposure.

Platforms worth evaluating

If you want a commercial EASM platform rather than assembling this yourself, I'd put these on the shortlist:

I would not select solely based on which vendor produces the largest asset count. The key question is whether the platform can distinguish your assets from the enormous amount of internet infrastructure it can observe, and whether it turns exposure into actionable remediation.

A practical evaluation

For a proof of concept, give each vendor the same limited set of known assets—say your primary domains and several known public IP ranges—and ask them to run for 2–4 weeks.

Measure:

• Unknown assets discovered
• False-positive rate
• Asset attribution accuracy
• Time to discover newly exposed assets
• Critical exposures identified
• Exploitability validation
• Prioritization quality
• Integration with your ticketing/vulnerability systems
• API quality
• Coverage of cloud, SaaS, subsidiaries and acquisitions
• Operational effort required from your security team

The most important demo question I'd ask is:

“Show us the five externally exposed assets you believe pose the greatest real-world risk to us, explain why, and show exactly how you would get those risks remediated.”

That separates an internet asset inventory from an actual attack-surface reduction program.

If you tell me roughly your company size, cloud environment (AWS/Azure/GCP), existing security stack (e.g. Microsoft/CrowdStrike/Palo Alto/Tenable/Rapid7), and whether M&A/subsidiary discovery is important, I can narrow this to a 2–3 vendor recommendation and an evaluation scorecard.

To understand and mitigate an external attack surface, your team needs an External Attack Surface Management (EASM) solution . These platforms provide an continuous, outside-in "attacker's-eye view" of your public-facing infrastructure (domains, IPs, APIs, cloud buckets, and shadow IT) without requiring internal agents.

Leading EASM platforms cater to different organizational needs and existing security ecosystems:

• CyCognito is ideal for lean teams dealing with heavy shadow IT, offering seedless, automated discovery that correlates technical and attribution indicators.
• Palo Alto Cortex Xpanse fits large, complex enterprise environments that demand massive, continuous internet-scale scanning and automated active response.
• Microsoft Defender EASM is the most seamless fit for organizations already standardized on Azure, Microsoft Defender, and Microsoft Sentinel operations.
• Tenable Attack Surface Management integrates smoothly if you are already running vulnerability management programs within the Tenable ecosystem.
• IONIX excels at multi-entity organizations, complex subsidiaries, and mapping hidden digital supply chain dependencies.
• CrowdStrike Falcon Exposure Management / Surface unifies external asset discovery with endpoint telemetry for existing CrowdStrike users.

If you share your current security stack (e.g., Microsoft, CrowdStrike, Tenable) and whether your primary challenge is shadow IT discovery or subsidiary tracking , I can recommend the most tightly integrated vendor solution for your workflow.