Microsoft Defender External Attack Surface Management (EASM)
5 minutes
5 Questions
Microsoft Defender External Attack Surface Management (EASM) is a security solution that helps organizations discover and monitor their internet-facing assets and potential vulnerabilities from an attacker's perspective. This tool provides continuous visibility into your organization's external dig…Microsoft Defender External Attack Surface Management (EASM) is a security solution that helps organizations discover and monitor their internet-facing assets and potential vulnerabilities from an attacker's perspective. This tool provides continuous visibility into your organization's external digital footprint, identifying assets that may be unknown to your security team.
EASM works by scanning the internet to discover assets associated with your organization, including domains, subdomains, IP addresses, web applications, cloud resources, and third-party services. It maps these assets to create a comprehensive inventory of your external attack surface, which often extends beyond what internal asset management systems track.
Key capabilities of Microsoft Defender EASM include:
**Asset Discovery**: Automatically identifies internet-exposed infrastructure linked to your organization, including shadow IT and forgotten resources that could pose security risks.
**Vulnerability Detection**: Continuously scans discovered assets for known vulnerabilities, misconfigurations, and security weaknesses that attackers might exploit.
**Risk Prioritization**: Assigns risk scores to identified issues, helping security teams focus on the most critical vulnerabilities first based on potential impact and exploitability.
**Integration with Microsoft Security Stack**: EASM integrates seamlessly with Microsoft Sentinel and Microsoft Defender for Cloud, enabling unified security operations. Data from EASM can trigger alerts and automated responses through these platforms.
**Dashboard and Reporting**: Provides intuitive dashboards showing attack surface metrics, trending data, and detailed asset information for compliance and security assessments.
For Azure Security Engineers, EASM complements internal security monitoring by providing the external perspective that traditional tools miss. When combined with Microsoft Sentinel's SIEM capabilities and Defender for Cloud's workload protection, organizations gain comprehensive security coverage spanning both internal and external attack vectors. This holistic approach enables proactive threat hunting and reduces the risk of breaches through previously unknown external assets.
Microsoft Defender External Attack Surface Management (EASM)
Why is Microsoft Defender EASM Important?
In today's cloud-first world, organizations often have a sprawling digital footprint that extends beyond their known assets. Shadow IT, forgotten subdomains, exposed APIs, and legacy infrastructure create blind spots that attackers actively exploit. Microsoft Defender EASM provides continuous discovery and monitoring of your external-facing assets, helping security teams identify vulnerabilities before malicious actors do.
What is Microsoft Defender EASM?
Microsoft Defender External Attack Surface Management (EASM) is a security solution that continuously discovers and maps your organization's digital attack surface from an outside-in perspective. It identifies:
• Unknown assets - domains, subdomains, and IP addresses you may not be tracking • Exposed services - web applications, APIs, and ports visible from the internet • Vulnerabilities - CVEs, misconfigurations, and security weaknesses • SSL/TLS issues - expired certificates and weak encryption • Infrastructure details - hosting providers, ASNs, and technology stacks
How Microsoft Defender EASM Works
1. Discovery Seeds: You provide initial discovery seeds such as domain names, IP addresses, or ASN numbers that belong to your organization.
2. Automated Discovery: EASM uses these seeds to recursively discover related infrastructure, including subdomains, linked domains, and associated IP ranges.
3. Continuous Monitoring: The solution continuously scans discovered assets to identify changes, new vulnerabilities, and emerging risks.
4. Attack Surface Insights: EASM provides dashboards and reports showing your attack surface composition, high-priority vulnerabilities, and compliance status.
5. Integration: EASM integrates with Microsoft Sentinel and other security tools for automated response and investigation workflows.
Key Features for the AZ-500 Exam
• Asset Discovery - Identifies internet-facing assets including domains, hosts, pages, and IP blocks • Vulnerability Detection - Scans for known CVEs and common security misconfigurations • Dashboard Insights - Provides attack surface summary with risk prioritization • Inventory Management - Categorizes assets by state (approved, candidate, dependency, requires investigation) • Data Connectors - Exports data to Microsoft Sentinel for SIEM correlation
Exam Tips: Answering Questions on Microsoft Defender EASM
1. Understand the Outside-In Perspective: EASM views your organization as an attacker would. When questions ask about discovering unknown internet-facing assets, EASM is likely the correct answer.
2. Know the Discovery Seeds: Remember that EASM requires initial seeds (domains, IPs, ASNs) to begin discovery. Questions may test your understanding of how discovery is initiated.
3. Differentiate from Other Defender Products: EASM focuses on external assets, while Defender for Cloud focuses on cloud workloads. Defender for Endpoint protects devices. Ensure you select EASM for external attack surface scenarios.
4. Asset States Matter: Know the four asset states - Approved Inventory, Candidate, Dependency, and Requires Investigation. Exam questions may ask how assets are classified.
5. Integration Scenarios: When questions mention correlating external attack surface data with SIEM capabilities, remember that EASM integrates with Microsoft Sentinel.
6. Use Case Recognition: If a scenario describes discovering shadow IT, forgotten subdomains, or mapping internet-exposed infrastructure, EASM is typically the solution being tested.
7. Licensing Awareness: EASM is a separate Azure service with its own pricing model based on the number of assets discovered. Be aware this is not included in standard Defender for Cloud plans.