Microsoft Defender External Attack Surface Management for Small Businesses in Berlin

Most organizations understand their internal attack surface — the assets they manage, patch, and monitor on their own infrastructure. The external attack surface is a different problem: internet-facing assets that are known to attackers through passive reconnaissance before your security team is even aware they exist. Forgotten subdomains, expired certificates presenting as active services, development environments promoted to production without security review, third-party services acquiring your domain through acquisitions, misconfigured cloud storage with public read access — these are the categories of exposure that Microsoft Defender External Attack Surface Management (EASM) is built to discover and surface for remediation. For small businesses in Berlin operating cloud workloads, SaaS integrations, and web properties across multiple registrars and hosting providers, EASM provides the outside-in perspective that internal vulnerability management tools structurally cannot provide.

How Microsoft Defender EASM Discovers Your Attack Surface

EASM builds an organization’s external attack surface through recursive discovery starting from seed assets — domains, IP ranges, email domains, or ASN numbers that the organization owns. From these seeds, EASM applies the same techniques that attackers use for reconnaissance: DNS enumeration to find subdomains, certificate transparency log analysis to identify SSL/TLS certificates issued for organizational domains, WHOIS data correlation to link registrant information across registrars, IP-to-domain relationship analysis, and crawling of discovered web properties to identify additional assets and technologies. The result is a continuously updated inventory of internet-facing assets, including assets the organization may not have been tracking actively.

The EASM discovery engine runs continuously rather than on a scheduled scan cycle, reflecting the reality that the external attack surface changes dynamically as new services are deployed, cloud resources are provisioned, and third-party acquisitions bring new domains under organizational scope. Assets are classified by type — domain, host, IP address, IP block, SSL certificate, WHOIS contact, web component, web cookie, subdomain — and enriched with metadata including registration dates, hosting providers, detected technologies, observed open ports, and SSL/TLS certificate validity and chain information.

Risk Scoring and Prioritization

EASM assigns vulnerability severity classifications to discovered assets based on observed risk factors: CVEs associated with detected software versions, expired or expiring SSL/TLS certificates, open ports associated with risky protocols, assets on IP reputation blocklists, misconfigured web security headers, and exposed development infrastructure. The attack surface dashboard provides a prioritized view of critical, high, medium, and low-risk observations across the full discovered inventory, enabling security teams to focus remediation effort on exposures with the highest potential impact rather than working through undifferentiated scan output.

For organizations that have undergone mergers, acquisitions, or rapid cloud expansion, EASM’s inventory frequently surfaces assets that internal teams did not know existed. A subdomain pointing to a decommissioned service provider — a classic subdomain takeover candidate — or a forgotten test environment running an unpatched web server represent the categories of high-impact, low-effort targets that threat actors prioritize for initial access. EASM surfaces these before attackers exploit them, at a discovery cost that would take manual research teams weeks to replicate.

Integration with Microsoft Defender for Cloud and Sentinel

Microsoft Defender EASM integrates with Microsoft Defender for Cloud to provide external context for cloud workload security recommendations. When Defender for Cloud identifies a security finding on an Azure resource, EASM data can surface whether that resource has associated internet-facing exposure — making the finding’s exploitability context immediately clear rather than requiring a separate external scan. For organizations using Microsoft Sentinel as their SIEM, EASM data can be exported via the Defender for Cloud connector to enrich incident context with external attack surface observations, helping analysts understand whether compromised assets had pre-existing external exposure before the incident occurred.

The combination of EASM’s continuous external discovery, Microsoft Defender for Endpoint’s internal endpoint vulnerability data, and Microsoft Defender for Cloud’s cloud workload posture management creates a unified view of organizational exposure that spans the full attack surface from external internet-facing assets through cloud workloads to individual endpoints. For security teams that need to answer “where are we most exposed and what could an attacker do with initial access to any of those exposures,” this integrated view provides the context that isolated product dashboards cannot.

Licensing and Access

Microsoft Defender EASM is available as a standalone Azure service billed based on the number of billable assets in the organization’s inventory, with a per-asset per-month pricing model that scales with the size of the discovered attack surface. EASM is also included in the Microsoft Defender for Cloud enhanced security features package for organizations already using Defender for Cloud’s Defender plans for servers, containers, or databases. For organizations evaluating EASM, Microsoft provides a trial workspace that enables full discovery and risk assessment without commitment — the discovery results alone frequently justify continued use by surfacing previously unknown exposures.

ITEXPERTS Berlin: EASM Deployment and Attack Surface Reduction

ITEXPERTS Berlin deploys and manages Microsoft Defender EASM for small and medium businesses in the Berlin area, covering initial workspace configuration and seed asset definition, discovery result triage and false positive management, integration with Microsoft Defender for Cloud and Sentinel, and ongoing attack surface reduction guidance as new exposures are identified. For businesses that have not previously conducted external attack surface assessment, an initial EASM discovery frequently produces findings that require immediate remediation — we provide the triage and remediation prioritization support needed to close those gaps efficiently. Contact us to initiate an external attack surface assessment for your organization.