Microsoft Defender for Endpoint: What UK SMEs Need to Know

Understanding Microsoft Defender for Endpoint

For UK businesses building a robust cybersecurity posture, understanding Microsoft's endpoint security products is essential. Microsoft Defender for Endpoint (MDE) is Microsoft's enterprise-grade endpoint detection and response platform, but it is not the only product in the Defender family — and the differences between the various Defender products are a common source of confusion. According to the DSIT Cyber Security Breaches Survey 2025, 43% of UK businesses experienced a cybersecurity breach or attack in the past 12 months, making effective endpoint protection a critical priority for organisations of every size.

The Defender brand encompasses several distinct products. Windows Defender Antivirus is the consumer-grade protection built into Windows 10 and 11 — it provides basic malware detection using signature matching but lacks centralised management, behavioural analysis, and the advanced endpoint detection and response capabilities that business environments require. Microsoft Defender for Endpoint is the enterprise platform, while Microsoft Defender for Business is a separate product designed specifically for SMEs with up to 300 users.

Microsoft Defender for Endpoint: Plans and Capabilities

Microsoft Defender for Endpoint is available in two tiers. Plan 1 (MDE P1) provides next-generation antivirus with cloud-delivered threat intelligence, attack surface reduction rules, and device control. Plan 2 (MDE P2) adds endpoint detection and response with full telemetry, automated investigation and remediation, threat and vulnerability management, and proactive threat hunting capabilities. MDE P2 is included in Microsoft 365 E5 and Microsoft 365 Defender licences, making it primarily an enterprise product.

The threat and vulnerability management module in MDE P2 continuously assesses the security posture of enrolled endpoints, identifying unpatched software, configuration weaknesses, and exposure to known vulnerabilities. This provides security teams with a prioritised view of which endpoints require attention, based on the severity and exploitability of identified weaknesses. The automated investigation capability analyses alerts and either resolves them automatically or recommends specific remediation actions, reducing the manual workload on security analysts.

Key MDE P2 Capabilities

• Behavioural detection using machine learning and Microsoft's global threat intelligence network
• Endpoint detection and response with device isolation, process termination, and file quarantine
• Automated investigation that analyses alert chains and recommends or executes remediation
• Threat and vulnerability management for continuous posture assessment
• Proactive threat hunting using advanced query tools across endpoint telemetry
• Integration with Microsoft Sentinel for SIEM and extended detection and response (XDR) scenarios

Microsoft Defender for Business: The SME Alternative

For most UK SMEs, Microsoft Defender for Business — included in Microsoft 365 Business Premium — is the appropriate choice. Defender for Business provides capabilities equivalent to MDE P2, packaged in an interface and configuration model designed for organisations without dedicated security teams. It includes next-generation antivirus with cloud-delivered intelligence, endpoint detection and response with device isolation, attack surface reduction rules, automated investigation, and centralised management through the Microsoft 365 Defender portal.

The endpoint security capabilities in Defender for Business draw on Microsoft's cloud threat intelligence, built from telemetry across hundreds of millions of endpoints globally. When a new threat is identified anywhere in this network, detection signatures and behavioural indicators are distributed to all connected endpoints within minutes. This cloud-first approach provides protection against emerging threats far more rapidly than traditional antivirus products that rely on periodic signature database updates.

Attack Surface Reduction Rules

One of the most valuable features in both MDE and Defender for Business is attack surface reduction (ASR) rules. These rules proactively block common attack techniques at the source, preventing many attacks before detection is even needed. ASR rules can block Office applications from spawning executable processes, which prevents a wide range of macro-based attacks. They can block credential theft from the Windows Local Security Authority Subsystem Service (LSASS), preventing attackers from harvesting credentials stored in memory. They can block potentially obfuscated script execution and executable content from email attachments.

With 85% of breaches involving phishing (DSIT 2025), ASR rules that block email-borne attack techniques provide significant protective value. However, ASR rules must be deliberately enabled and configured — the default deployment of Defender for Business does not activate all available rules, and many organisations run them in audit-only mode indefinitely, which provides visibility but no protection.

Configuration and Licensing Considerations

Defender for Business and MDE are not plug-and-play products. The default configuration provides basic protection, but the full security value requires deliberate configuration beyond initial deployment. AMVIA configures Defender for Business to Microsoft's recommended security baseline, which includes enabling ASR rules in block mode rather than audit-only, configuring controlled folder access to protect critical directories against ransomware encryption, enabling network protection to block connections to known malicious domains, and reviewing exclusions carefully to avoid inadvertently weakening detection.

From a licensing perspective, Defender for Business is included in Microsoft 365 Business Premium at no additional endpoint security cost for businesses with up to 300 users. This makes it one of the most cost-effective enterprise-grade endpoint security solutions available to UK SMEs. Businesses on Microsoft 365 Business Basic or Standard do not receive Defender for Business and would need to add it as a standalone licence or upgrade to Business Premium. The average cost of a data breach for UK organisations was £3.4 million in 2024 (IBM 2024), making the investment in proper endpoint security configuration highly worthwhile.

Alert Management and Response

Defender for Business generates security alerts when threats are detected. These alerts require investigation — not every alert represents a genuine threat, and genuine threats often require response action beyond what automated remediation handles. Without a managed service, alerts frequently accumulate without being investigated, or are dismissed without proper analysis. Only 14% of UK businesses have a formal incident response plan (DSIT 2025), which means the majority have no structured process for handling the alerts their security tools generate.

AMVIA monitors Defender for Business alerts through AmviaIQ, investigates significant detections, and takes containment action when threats are confirmed. This transforms Defender for Business from a detection tool that generates alerts into a managed security control that actively responds to threats. For businesses that want an additional layer of endpoint analysis, AMVIA can deploy Huntress EDR alongside Defender for Business, providing a second opinion on endpoint alerts and a dedicated managed analyst layer.

Deployment and Enrolment via Intune

All Defender for Business and MDE devices are managed centrally through Microsoft Intune and the Microsoft 365 Defender portal. Intune handles device enrolment, policy deployment, and compliance monitoring, while the Defender portal provides the security-specific view of alerts, investigations, and endpoint health. This centralised management model eliminates the need for local device-by-device configuration and ensures that security policies are applied consistently across the entire managed device estate.

Device enrolment can be automated through Windows Autopilot for new devices or through group policy and scripting for existing estates. Once enrolled, devices receive security baseline configurations automatically, ensuring that every endpoint meets the same minimum security standard from the moment it joins the managed environment. Compliance policies in Intune can block non-compliant devices from accessing corporate resources through Conditional Access, ensuring that devices with outdated configurations or disabled protections cannot access business data until they are brought back into compliance.

AMVIA handles the full deployment process — enrolling devices in Intune, deploying Defender for Business agents, configuring security baselines, and validating that all endpoints are reporting correctly to the management portal. Ongoing management includes monitoring device compliance, investigating security alerts, and adjusting configuration as Microsoft releases new capabilities and as the threat landscape evolves. Contact AMVIA on 0333 733 8050 to discuss Defender for Business configuration for your business.