Exclude File Extensions in Windows Defender via Registry

Configuring Microsoft Defender Antivirus to ignore specific file extensions can help reduce false positives, lower CPU overhead, and streamline development workflows. This guide outlines the exact steps to create file extension exclusions directly in the Windows Registry using the Registry Editor (regedit), ensuring that Defender bypasses scanning for your specified file types.

Step 1: Open the Registry Editor

  1. Press Windows Key + R to open the Run dialog box.
  2. Type regedit and press Ctrl + Shift + Enter (or click OK) to open the Registry Editor with administrative privileges.
  3. Click Yes if prompted by User Account Control (UAC).

Step 2: Navigate to the Windows Defender Exclusions Key

Paste the following path into the address bar at the top of the Registry Editor and press Enter:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender

Step 3: Create Missing Keys (If Necessary)

If the Exclusions and Extensions keys do not exist under Windows Defender, you must create them manually: 1. Right-click the Windows Defender folder, select New > Key, and name it Exclusions. 2. Right-click the newly created Exclusions folder, select New > Key, and name it Extensions.

The full path should now be: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Exclusions\Extensions

Step 4: Add the File Extension Exclusion

  1. Select the Extensions key in the left sidebar.
  2. Right-click an empty area in the right-hand pane, select New, and choose String Value (REG_SZ).
  3. Set the name of the new value to the file extension you want to exclude (for example, log, bak, or iso without leading periods).
  4. Double-click the newly created value name and set its Value data to 0.
  5. Click OK to save the entry.

Step 5: Apply the Changes

To apply the changes, restart your computer or restart the Microsoft Defender Antivirus Service via the Services console (services.msc). Once restarted, Windows Defender will permanently skip real-time and scheduled scans for files matching the configured extensions.