1. Onboarding & Sensor Health

  • Onboarding Methods: In an enterprise environment, use Intune (Configuration Profiles) or Group Policy for automated deployment. Local scripts are available for testing but should be avoided for production scale.
  • Sensor Health Monitoring: Regularly check the “Device Inventory” for devices in an “Inactive” or “No sensor data” state. This usually indicates connectivity blocks to MDE backend URLs or the SENSE service being disabled.
  • Offboarding Governance: When a device is decommissioned, it must be offboarded to prevent it from negatively impacting the organization’s exposure score. Note that offboarding scripts have a 30-day expiration period for security reasons.

2. Attack Surface Reduction (ASR)

  • ASR Rules: Implement rules to close common entry points for malware (e.g., “Block credential stealing from the Windows local security authority subsystem”).
  • Phased Rollout: Always deploy ASR rules in Audit Mode first. Use the “Attack Surface Reduction” report in the Defender portal to identify potential business-critical software that would be blocked before switching to Enforcement Mode.
  • Exclusions: Manage ASR exclusions at the policy level rather than globally to maintain a tight security posture.

3. Vulnerability Management (TVM)

  • Exposure Score: Monitor this real-time metric to understand the organization’s current risk level relative to the threat landscape.
  • Security Recommendations: Focus on “Top Security Recommendations” which are prioritized based on active exploits in the wild and the business impact on the tenant.
  • Software Inventory: Use the inventory to track end-of-life (EOL) software and missing patches across Windows, macOS, and Linux endpoints.

4. Detection & Response (EDR)

  • Alert Triage: MDE correlates related alerts into a single Incident, providing a full story of the attack chain. Prioritize incidents over individual alerts.
  • Live Response: A command-line console used to remotely collect forensic data, run scripts, or remediate threats on a compromised endpoint in real-time.
  • Automation Levels: Configure “Device Groups” with specific automation levels (e.g., “Full - remediate threats automatically”) to allow AIR (Automated Investigation and Response) to resolve known threats without manual intervention.

5. Next-Generation Protection (Antivirus)

  • Cloud-Delivered Protection: Must be enabled to provide near-instant protection against new and emerging malware that hasn’t been seen by local signatures yet.
  • Tamper Protection: A critical tenant-wide setting that prevents malicious apps (or local admins) from disabling Microsoft Defender antivirus or EDR sensors.

6. Essential PowerShell Cmdlets (Windows Defender Module)

  • Client Status:
    • Get-MpComputerStatus (Verify if real-time protection and MDE sensor are active)
  • Configuration Review:
    • Get-MpPreference (View current exclusions and scan schedules)
  • Diagnostic Logging:
    • Get-MpThreatDetection (Review a history of threats detected on the local machine)
  • Connectivity Troubleshooting:
    • Start-Process "C:\Program Files\Windows Defender\MpCmdRun.exe" -ArgumentList "-ValidateEdgeConnectivity" (Validates that the device can reach MDE cloud service endpoints)