Microsoft Defender for Endpoint: What UK SMEs Need to Know

Microsoft's Endpoint Security Product Family

Microsoft offers multiple endpoint security products under the Defender brand, which can be confusing. Windows Defender Antivirus is built into Windows 10 and 11 and provides basic consumer-grade malware protection. It is not the same as Microsoft's enterprise security products and lacks centralised management, EDR capability, and attack surface reduction rules.

Microsoft Defender for Endpoint (MDE) is the enterprise platform, available in two tiers: Plan 1 (P1) provides next-generation antivirus, attack surface reduction, and device control. Plan 2 (P2) adds endpoint detection and response (EDR), automated investigation and remediation, threat and vulnerability management, and proactive threat hunting. MDE P2 is included in Microsoft 365 E5 and Microsoft 365 Defender licences.

Microsoft Defender for Business is a separate product introduced specifically for SMEs — businesses with up to 300 users. It is included in Microsoft 365 Business Premium and provides MDE P2-equivalent capabilities in an interface and configuration model designed for organisations without dedicated security teams. For most UK SMEs, Defender for Business is the appropriate product.

What Defender for Business Provides

Microsoft Defender for Business (included in M365 Business Premium) provides the following capabilities: next-generation antivirus with cloud-delivered threat intelligence; endpoint detection and response with device isolation capability; attack surface reduction rules that block common attack techniques; automated investigation that analyses alerts and recommends or takes remediation actions; and centralised management through the Microsoft 365 Defender portal.

The attack surface reduction (ASR) rules in Defender for Business are particularly valuable for SMEs. Rules can block: Office applications from spawning executable processes (a common macro-based attack vector); credential theft from the Windows Local Security Authority (LSASS); potentially obfuscated script execution; and executable content from email attachments. When correctly configured, ASR rules prevent a significant proportion of attacks before detection is needed.

Configuration Is Critical

Defender for Business and MDE are not plug-and-play — the default configuration provides basic protection, but the full security value requires deliberate configuration. AMVIA configures Defender for Business to Microsoft's recommended security baseline, which includes enabling ASR rules at appropriate levels, configuring controlled folder access to protect against ransomware, enabling network protection, and configuring exclusions carefully to avoid inadvertently weakening protection.

A poorly configured Defender for Business deployment — for example, one with excessive exclusions or ASR rules in audit-only mode — provides substantially weaker protection than a correctly configured deployment. AMVIA's configuration approach is based on Microsoft's security baseline and NCSC guidance.

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 (false positives occur), and genuine threats require response action beyond what automated remediation handles. Without a managed service, alerts can accumulate without being investigated.

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 actually responds to threats.

Key Considerations for UK SMEs

• Verify which Defender product your business has — Windows Defender Antivirus is not the same as Defender for Business or MDE
• M365 Business Premium includes Defender for Business — if you are on Business Premium, you already have enterprise EDR at no additional cost
• Configuration matters — default Defender for Business settings are not optimal; AMVIA configures to Microsoft's security baseline
• Attack surface reduction rules should be enabled — they prevent many attacks before detection is needed
• Alerts need management — Defender for Business is most effective when alerts are monitored and investigated by a qualified team

How AMVIA Can Help

AMVIA deploys and manages Microsoft Defender for Business as part of its managed cybersecurity service. We configure Defender for Business to Microsoft's recommended security baseline, enrol all managed endpoints, enable attack surface reduction rules, and monitor alerts through AmviaIQ. Security incidents detected by Defender for Business are investigated by AMVIA's security team and responded to without waiting for you to raise a support ticket. Contact AMVIA on 0333 733 8050 to discuss Defender for Business configuration for your business.