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Disable Defender Antivirus service high-priority startup

Overview​

About this script

This script improves your privacy on Windows.

These changes use Windows system commands to update your settings.

This script configures Defender Antivirus to start with a lower priority.

By default, Windows runs the Defender Antivirus service (also called the Antimalware Service 1) with normal priority 2 3 4 5. This script changes the startup priority to low 2 3 4 5.

This enhances privacy by reducing background scanning and potentially limiting data collection during Windows startup. It may improve system performance by reducing resource usage for the antivirus during startup 2 3 4 5.

Lowering the priority may delay antivirus initialization, potentially leaving a brief window where the system is less protected. However, MITRE, a leading cybersecurity organization, does not consider this a security vulnerability 5.

Caution

This action may delay antivirus protection initialization.

Technical Details​

This script sets the following registry keys to configure Group Policy Objects (GPO):

  • For recent Windows versions: HKLM\Software\Policies\Microsoft\Windows Defender!AllowFastServiceStartup 2 4
  • For older Windows versions: HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware!AllowFastServiceStartup 3

This script uses Batch (batchfile) scripting language.

Use with Caution

This script is only recommended if you understand its implications. Some non-critical or features may no longer function correctly after running this script.

Implementation Details

  • Language: batch

  • Required Privileges: Administrator rights

  • Compatibility: Windows only

  • Reversibility: Can be undone using provided revert script

Explore Categories​

This action belongs to Disable Defender Antivirus service category. This category disables the Defender Antivirus service and its related components. This service is also referred to as Microsoft Defender Antivirus Service and Windows Defender Service. It is a core component of Microsoft Defender Antivirus, essential for its operation. Using these... Read more on category page ▶

Apply now​

Choose one of three ways to apply:

  1. Automatically via privacy.sexy: The easiest and safest option.
  2. Manually by downloading: Requires downloading a file.
  3. Manually by copying: Advanced flexibility.

Alternative 1. Apply with Privacy.sexy​

privacy.sexy is free and open-source application that lets securely apply this action easily.

Open privacy.sexy

You can fully restore this action (revert back to the original behavior) using the application.

privacy.sexy instructions
  1. Open or download the desktop application
  2. Search for the script name: Disable Defender Antivirus service high-priority startup.
  3. Check the script by clicking on the checkbox.
  4. Click on Run button at the bottom of the page.

Alternative 2. Download​

Irreversible Changes

This script is irreversible, meaning there is no straightforward method to restore changes once applied. Exercise caution before running, restoring it may not be possible.

  1. Download the script file by clicking on the button below:

    Download script

  2. Run the script file by clicking on it.

Download revert script​

This file restores your system to its original state, before this script is applied.

Download restore script

Alternative 3. Copy​

This is for advanced users. Consider automatically applying or downloading the script for simpler way.

  1. Open Command Prompt as administrator.
HELP: Step-by-step guide

  1. Click on Start menu

  2. Type cmd

  3. Right click on Command Prompt select Run as administrator

  4. Click on Yes to run Command Prompt

Animation showing how to open terminal as administrator on Windows 11

  1. Copy the following code:
Code to apply changes
:: Set the registry value: "HKLM\Software\Policies\Microsoft\Windows Defender!AllowFastServiceStartup"
PowerShell -ExecutionPolicy Unrestricted -Command "$registryPath = 'HKLM\Software\Policies\Microsoft\Windows Defender'; $data = '0'; reg add 'HKLM\Software\Policies\Microsoft\Windows Defender' /v 'AllowFastServiceStartup' /t 'REG_DWORD' /d "^""$data"^"" /f"
:: Set the registry value: "HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware!AllowFastServiceStartup"
PowerShell -ExecutionPolicy Unrestricted -Command "$registryPath = 'HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware'; $data = '0'; reg add 'HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware' /v 'AllowFastServiceStartup' /t 'REG_DWORD' /d "^""$data"^"" /f"
  1. Right click on command prompt to paste it.
  2. Press Enter to apply remaining code.

Copy restore code​

Copy and run the following code to restore changes:

Revert code
:: Delete the registry value "HKLM\Software\Policies\Microsoft\Windows Defender!AllowFastServiceStartup"
PowerShell -ExecutionPolicy Unrestricted -Command "reg delete 'HKLM\Software\Policies\Microsoft\Windows Defender' /v 'AllowFastServiceStartup' /f 2>$null"
:: Delete the registry value "HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware!AllowFastServiceStartup"
PowerShell -ExecutionPolicy Unrestricted -Command "reg delete 'HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware' /v 'AllowFastServiceStartup' /f 2>$null"

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