Your organization has more internet-facing assets than your security team knows about. Learn how EASM discovers and monitors these assets before attackers exploit them.
• EASM discovers internet-facing assets from the attacker’s perspective, finding forgotten subdomains, shadow IT, and misconfigurations your team doesn’t know exist.
• Only 54% of edge vulnerabilities get fully remediated, giving attackers a wide window to exploit exposed assets.
• EASM shows what’s exposed but doesn’t assess vulnerabilities or track stolen credentials.
• Pair it with vulnerability scanning and credential monitoring for a fuller picture of external risk.
Your attack surface grows every time someone spins up a cloud instance, adds a SaaS tool, or connects a vendor. Security teams can’t keep up.
The average organization has 30% more external assets than documented. You can’t patch what you don’t know exists.
Vulnerability exploitation now accounts for 20% of all initial access vectors, up from 15% the prior year (Verizon’s 2025 Data Breach Investigations Report). VPNs and edge devices are common targets.
EASM gives security teams the same view of their organization that attackers have. Here’s how it works and why traditional tools miss what matters most.
Your security perimeter isn’t what it used to be. Every cloud service, remote access portal, and SaaS integration creates another potential entry point for attackers.
External attack surface management (EASM) is the continuous process of discovering and monitoring all internet-facing assets visible to attackers outside your network. EASM platforms automatically find forgotten subdomains, misconfigured cloud resources, exposed APIs and edge devices, giving security teams the same view of their organization that threat actors have.
EASM operates from the attacker’s perspective. It scans the internet the same way threat actors do, looking for assets associated with your organization. No internal access required. No agents to deploy. Just visibility into what’s publicly exposed.
This matters because traditional security tools only protect what you point them at. Vulnerability scanners check known assets. Firewalls protect defined perimeters. But attackers aren’t limited to your documented inventory. They scan everything, and they find assets your security team forgot existed.
EASM follows a four-stage cycle that runs continuously because your attack surface changes daily.
EASM platforms scan the internet for everything connected to your organization. They use DNS enumeration to map subdomains and records. Certificate transparency logs reveal domains using your SSL certificates. Reverse IP lookups find other domains hosted on your infrastructure. Public scan databases like Shodan and Censys show exposed services. Historical DNS records uncover assets that were previously connected to your network.
The goal is comprehensive inventory. Every subdomain, every IP address, every cloud resource, every third-party service that touches your infrastructure.
Once discovered, assets need context. What technology stack does each asset run? Who owns it? Is it production or development? What data does it handle?
Classification determines risk priority. A forgotten marketing microsite matters less than an exposed database server. An abandoned staging environment with production credentials matters more than both.
EASM tools perform external security checks on discovered assets. They identify open ports, exposed services, SSL certificate issues, and common misconfigurations. They fingerprint software versions and flag outdated components likely to have known CVEs.
This isn’t vulnerability scanning. EASM shows what’s visible from outside your network. Determining actual exploitability requires traditional scanners with deeper access.
Attack surfaces change daily. New cloud resources appear. Configurations change. Certificates expire. Services get accidentally exposed.
Continuous monitoring catches these changes as they happen. You find out about new exposures in hours, not months. That’s the difference between proactive security and incident response.
EASM finds assets that traditional security tools miss because they were never in scope to begin with.
Forgotten subdomains and domains: That conference microsite from three years ago. The product launch page that’s still live. Acquired company domains that were never properly integrated.
Shadow IT cloud resources: Developers spin up cloud instances for testing and forget about them. Marketing teams create landing pages on third-party platforms. These resources often have weak security controls and direct connections to production systems.
Exposed development and staging environments: Test environments with production data. Staging servers with default credentials. Development APIs without authentication.
Misconfigured cloud storage: Public S3 buckets. Azure blob containers with anonymous access. Google Cloud Storage buckets indexed by search engines.
APIs without proper authentication: Internal APIs accidentally exposed to the internet. Legacy endpoints that predate modern security requirements. Third-party integrations with overly permissive access.
Expired or misconfigured SSL certificates: Certificates that expired without anyone noticing. Mixed content issues. Weak cipher configurations.
Open ports running unnecessary services: Database ports exposed directly to the internet. Administrative interfaces without proper access controls. Legacy services that should have been decommissioned.
Third-party service connections: Vendor integrations that extend your attack surface. Partner APIs with excessive permissions. Supply chain connections that put your data at risk when vendors get breached.
The data makes the case clearly.
Vulnerability exploitation is accelerating. It now represents 20% of initial breach access, up from 15% the previous year (Verizon’s 2025 Data Breach Investigations Report). Attackers are actively scanning for exploitable assets.
Edge devices are prime targets. VPNs and edge devices account for 22% of these attacks. They sit at your network perimeter, directly exposed to the internet.
Remediation is failing. Only 54% of edge device vulnerabilities were fully remediated during the DBIR study period. The median time to remediate vulnerabilities is 32 days. That’s a month-long window for exploitation.
Third-party risk is expanding. Third-party involvement in breaches doubled to 30% of all breaches (2025 DBIR). Your attack surface extends into every vendor and partner connection.
Unknown assets are under attack. Research consistently shows that 76% of organizations have experienced attacks on unknown or unmanaged assets. You can’t defend what you don’t know exists.
The cost is measurable. Organizations using attack surface management tools reduced breach costs by $160,547 on average (IBM’s 2025 Cost of a Data Breach Report). The global average breach cost hit $4.88 million.
EASM and internal attack surface management serve different purposes. You need both.
| Factor | EASM | Internal ASM |
|---|---|---|
| Perspective | Attacker’s view (outside-in) | Defender’s view (inside-out) |
| Assets covered | Internet-facing only | Behind the firewall |
| Access required | None (scans from outside) | Agents, network access |
| Primary discovery | Unknown assets | Known asset inventory |
| Threat model | External attackers | Lateral movement, insiders |
EASM focuses on what attackers see before they breach your network. Internal ASM focuses on containing attackers who get past the perimeter.
Most breaches follow a pattern: initial access through an external vulnerability, then lateral movement through internal systems. EASM addresses the first stage. Internal controls address the second.
CAASM (Cyber Asset Attack Surface Management) takes a broader approach.
CAASM (Cyber Asset Attack Surface Management) pulls data from your existing security tools to show all assets - internal and external - in one view. Where EASM scans from outside your network, CAASM integrates with internal systems to build a unified asset inventory.
EASM focuses exclusively on external assets. It works without internal access, discovering assets the way attackers do. It’s faster to deploy and provides immediate value for external visibility.
CAASM aggregates data from existing security tools. SIEMs, vulnerability scanners, endpoint agents, cloud security tools. It correlates this data to build a complete asset inventory across internal and external environments.
When to use each:
Many organizations start with EASM for quick wins, then expand to CAASM as their security program matures.
EASM and vulnerability scanners are complementary, not competing tools.
Vulnerability scanners check known assets for known vulnerabilities. They’re deep but narrow. You point them at specific systems, and they identify CVEs, misconfigurations, and security weaknesses. They need to know what to scan.
EASM discovers assets you didn’t know to scan. It’s broad but shallow. It finds the forgotten server, the shadow IT application, the misconfigured cloud resource. Then you add those discoveries to your vulnerability scanner’s scope.
The workflow is:
Without EASM, vulnerability scanners only cover documented assets. With EASM, you scan everything that’s actually exposed.
EASM solves problems that traditional security tools can’t touch.
Developers spin up cloud resources without security review. They need infrastructure fast, and cloud providers make provisioning trivial. Those resources often connect to production systems, use weak credentials, and never get proper security controls.
EASM finds these resources by scanning from outside. It doesn’t matter that they’re not in your asset inventory. If they’re on the internet and connected to your organization, EASM discovers them.
Most organizations use multiple cloud providers. AWS, Azure, GCP, plus specialized SaaS platforms. Each environment has different security controls, different APIs, different visibility tools.
EASM abstracts this complexity. It scans the internet and finds what’s exposed, regardless of which cloud provider hosts the asset. One view of your external footprint across all environments.
Acquired companies bring unknown infrastructure. Legacy systems, abandoned projects, undocumented integrations. Security due diligence catches some of this, but not everything.
EASM discovers assets associated with acquired domains and IP ranges. It finds the infrastructure that wasn’t documented in the acquisition process.
Partner integrations extend your attack surface. Vendor APIs with excessive permissions. Supply chain connections that put your data at risk when vendors get breached. Third-party involvement in breaches doubled to 30% (2025 DBIR).
EASM identifies third-party services connected to your infrastructure. It provides visibility into connections that could become attack paths. Third-party cyber risk management extends this visibility to monitor vendor security postures.
Assets appear and disappear faster than manual inventory can track. Containerized workloads spin up and down. Auto-scaling creates temporary resources. Development teams iterate rapidly.
Continuous EASM monitoring catches these changes in real-time. Static asset inventories are outdated the moment they’re completed.
EASM isn’t a complete security solution. Understanding its limitations helps you use it effectively.
EASM doesn’t perform deep vulnerability assessment. It identifies what’s exposed, but detailed vulnerability analysis requires traditional scanners with authenticated access.
EASM doesn’t understand business context automatically. It can find assets, but it doesn’t inherently know which ones matter most to your business. You need to add that context.
EASM doesn’t remediate issues. It discovers problems and provides visibility. Fixing those problems requires separate processes and tools.
EASM doesn’t catch credentials already leaked to attackers. It finds exposed assets, but attackers who already have stolen passwords or session tokens can bypass authentication entirely.
EASM doesn’t monitor what attackers are discussing. It shows what’s visible on the internet, but it doesn’t track dark web forums, criminal marketplaces, or threat actor communications.
These limitations point to where EASM needs complementary capabilities.
EASM tells you what attackers can see. But what about what they already have?
Leaked credentials bypass authentication entirely. An attacker with valid credentials doesn’t need to exploit vulnerabilities. They just log in. Your attack surface includes every credential that’s been exposed in breaches, sold on criminal marketplaces, or stolen by infostealer malware.
Breaches involving stolen credentials cost $4.81 million on average (IBM’s 2025 Cost of a Data Breach Report). Credential abuse remains the top initial access method (Verizon’s 2025 DBIR).
Session tokens are more dangerous than passwords. Modern infostealers don’t just capture passwords. They grab session cookies and authentication tokens that completely bypass multi-factor authentication. A stolen session token gives attackers immediate access without any login or MFA requirements.
Initial access brokers sell network entry points. Cybercriminals specialize in compromising networks, then selling that access to ransomware operators and other attackers. Your organization might already be compromised before any visible attack begins.
Complete external visibility requires both approaches. EASM finds exposed assets. Credential monitoring finds leaked passwords and session tokens. Dark web monitoring tracks when your organization’s data appears in criminal marketplaces.
Not all EASM tools are created equal. Here’s what matters when evaluating options.
Discovery accuracy: How comprehensive is asset discovery? Does the tool find assets across cloud providers, third-party services, and legacy infrastructure? False negatives matter more than false positives here.
Continuous monitoring frequency: How often does the tool scan? Daily scans miss changes that happen between checks. Real-time or near-real-time monitoring catches exposures faster.
Integration capabilities: Does the tool integrate with your existing security stack? SIEM integration for alerting. Vulnerability scanner integration for deeper assessment. Ticketing system integration for remediation workflows.
False positive management: How does the tool handle false positives? Can you tune it to reduce noise? High false positive rates lead to alert fatigue and missing real issues.
Third-party and vendor coverage: Does the tool monitor your supply chain? Can it track vendor security postures and alert on partner breaches?
Credential and dark web intelligence: Does the tool integrate with threat intelligence sources? Can it identify when your organization appears in data breaches or dark web marketplaces?
The best EASM solutions provide external visibility as part of a broader threat monitoring capability, not just asset discovery in isolation.
Your external attack surface is larger than your security team realizes. Cloud expansion, remote work, and third-party integrations have created blind spots that attackers actively exploit.
EASM provides the attacker’s perspective. It discovers internet-facing assets through the same techniques threat actors use. No internal access required. No blind spots from outdated asset inventories.
Key takeaways:
Start with visibility into your actual external footprint. Then extend that visibility to include what attackers already know about you.
Ready to see what attackers see? Check your dark web exposure to find leaked credentials, or book a demo to see how Breachsense provides complete external threat visibility.
External attack surface management (EASM) is the continuous process of discovering and monitoring all internet-facing assets visible to attackers outside your network. EASM platforms automatically find forgotten subdomains, misconfigured cloud resources, exposed APIs and edge devices, giving security teams the attacker’s view of their organization.
External attack surface management monitors internet-facing assets visible to anyone scanning from outside, like websites, APIs, and VPN portals. Internal attack surface management protects assets behind your firewall that attackers target after gaining initial access. EASM requires no internal access because it scans from the attacker’s perspective.
EASM works through a continuous four-stage cycle: discovery (scanning for all internet-facing assets), classification (categorizing by type, owner, and criticality), assessment (identifying open ports, SSL issues, and misconfigurations), and monitoring (detecting changes and new exposures in real-time). This process runs continuously because attack surfaces change daily.
The three main types are digital (networks, applications, cloud services, APIs), physical (hardware, devices, facilities), and human (employees targeted through social engineering). Digital attack surfaces grow as organizations adopt cloud services and remote work. Physical surfaces include any hardware attackers can access. Human surfaces are exploited through phishing and manipulation.
An external attack is any cyberattack originating from outside an organization’s network perimeter. External attackers probe internet-facing assets like websites, VPNs, and cloud services looking for vulnerabilities to exploit. Unlike insider threats, external attackers must first find a way into your network through exposed assets, stolen credentials, or social engineering.
The three most common indicators of compromise (IOCs) are unusual network traffic patterns (unexpected outbound connections or data transfers), suspicious file changes (new executables, modified system files, or unexpected registry changes), and anomalous user behavior (logins from unusual locations, access at odd hours, or privilege escalation attempts).
Attack Surface Management EASM Vulnerability Management External Threats Security Operations
Understanding Attack Surface Management Security teams spend millions protecting their networks. But they can only …
Typosquatting Domain Security Brand Protection Security Tools Phishing
What Is a Typosquatting Checker? You can’t defend against domains you don’t know exist. Typosquatting checkers solve …