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Windows Defender Overview

Jun 16, 2025

Overview

This lecture explains the built-in antivirus and anti-malware features in Windows, focusing on Microsoft Defender Antivirus and its main functions and configuration options.

Windows Defender Antivirus Overview

  • Microsoft Defender Antivirus is Windows’ built-in antivirus/anti-malware tool, installed and enabled by default.
  • Access Microsoft Defender through the Windows Security app under the "Virus & threat protection" section.
  • Previous names include Defender Antivirus, Windows Defender, and Microsoft Defender Antivirus.

Accessing Windows Security App

  • To open the app in Windows 11, search for “security” and select "Windows Security app."
  • The app includes multiple sections: account protection, firewall & network protection, app & browser control, and virus & threat protection.

Virus and Threat Protection Features

  • The main focus is on the "Virus & threat protection" section for antivirus management.
  • Real-time protection is enabled by default, scanning files as they are transferred in or out of the system.
  • Disabling antivirus protection is not recommended except for temporary troubleshooting.

Managing Real-Time Protection

  • To manage real-time protection, go to "Manage settings" under "Virus & threat protection settings."
  • You can enable/disable real-time protection, cloud-delivered protection, automatic sample submission, tamper protection, and controlled folder access.
  • Turning off real-time protection triggers a security warning, indicating your device is vulnerable.

Updating Antivirus Definitions

  • Antivirus relies on updated signatures (definitions) to detect threats.
  • Definitions update automatically but can be manually checked and updated under "Virus & threat protection updates."
  • In the updates section, you can see version information and force an update by clicking "Check for updates."

Key Terms & Definitions

  • Microsoft Defender Antivirus — Windows’ built-in antivirus and anti-malware protection.
  • Real-time protection — Continuous monitoring and scanning of files for threats as they move in and out of the system.
  • Definitions/Signatures — Files used by antivirus to identify the latest malware and threats.

Action Items / Next Steps

  • Practice accessing Windows Security app and familiarize yourself with the "Virus & threat protection" settings.
  • Manually check for definition updates to ensure antivirus is current.