How to Scan Removable Disks with Microsoft Defender

If you use a USB key on different PCs, it is important to make sure that you do not spread viruses between them.

Microsoft Defender makes it easy to scan your Windows computer for viruses and malware. Several scans are available, including quick and offline scan.

But did you know that you can also use Microsoft Defender to scan your removable and external drives? Here’s how.

What types of Microsoft Defender scans include removable drives?

You can configure Microsoft Defender to perform limited periodic scanning, even when you are using other antivirus software on your computer. These will be quick scans, covering areas where malware threats are commonly found. These scans may include removable drives if they are connected at the time.


Apart from a quick scan, Defender also allows full, custom, and offline scans. Custom scans can be used to check removable drives, but surprisingly your drives won’t be included in a full scan by default. If you want your removable drives to be scanned during a full scan, you need to enable it in the system settings.

How to scan removable drives with Microsoft Defender Custom Scan

A custom scan is the best option if you only want to scan specific files or folders. You can use the custom scan to check folders on a removable drive, but not the drive itself. Even when scanning a large folder, a custom scan should only take a few moments.

  1. In Windows 10, open the Settings app and click Update and security. This is Privacy and Security under Windows 11.
  2. Click on Windows Security then click on the Open Windows Security Button to launch the app.
  3. Open Virus & threat protection > Scan optionsthen select Custom analysis.
  4. Click it scan now then navigate to the removable or external drive you want to scan.

You cannot scan the entire drive, but you can check any file or folder on the drive. You can move all files in the drive into a single folder and use the custom scan to check the entire folder. Although not practical on a large 1TB drive, it is an option to more easily scan a smaller USB flash drive.

How to add removable drives to full scans in PowerShell

As mentioned earlier, a full antivirus scan will not include your connected external or removable drives by default. If you want external drives to be included in a full scan, you need to tell Defender to do so. There is no simple option in Windows Security to enable this feature, but you can enable it in PowerShell. Here’s how.

  1. Type PowerShell in Windows Search and choose Execute as administrator. You must have elevated privileges to make this type of change to Defender.
  2. In PowerShell, type the following: Set-MpPreference -DisableRemovableDriveScanning 0. This will enable scanning of the removable drive during a full scan.
  3. You can then close PowerShell. The next time you perform a full scan in Defender, all connected external drives will be scanned.
  4. If you want to disable removable drive scans, in PowerShell, type: Set-MpPreference -DisableRemovableDriveScanning 1.

Be aware that by adding a large external drive to a scan, the time required to complete the scan can increase significantly.

How to Include Removable Drives in a Full Scan with Group Policy Editor

As long as you are using a Pro or Enterprise edition of Windows, you can also enable removable drive scanning in the Local Group Policy Editor.

  1. Find and open the Local Group Policy Editor. This will be displayed as Edit Group Policy in the search results.
  2. In the panel to the left of the Group Policy Editor, select Setting up a computer. This displays a few folders in the main panel on the right.
  3. Click on Administrative Templates > Windows Components > Microsoft Defender Antivirus > Scan.
  4. Double-click Scan removable drives in the list of parameters displayed.
  5. In the new window that opens, change Not configured at Enabled. Click on Apply then click Ok.

You can then close the Local Group Policy Editor. The next time you perform a full scan in Defender, all attached removable drives will also be scanned. If you want to disable removable drive scanning, repeat the above steps, but change the setting to Not configured Where Disabled.

Scanning your removable drives in Microsoft Defender

It’s not always clear which of Microsoft Defender’s scanning options will include external or removable drives. And it’s surprising that a full scan doesn’t work by default. But with a simple change, your options for scanning your external drives and keeping your computer virus-free just got a whole lot better.

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Steven L. Nielsen