How to Configure Windows Sandbox Virtual Smart Card and WebAuthn via XML in Windows 11

Enterprise identity validation frequently requires hardware security keys (such as FIDO2 / WebAuthn tokens and PIV smart cards) for cryptographic logon and client certificate authentication. When developing authentication middleware, testing single sign-on (SSO) gateways, or inspecting enterprise software in an isolated environment, developers need Windows Sandbox to communicate with host security tokens. By authoring custom .wsb XML configuration files and enabling Remote Desktop security redirections, you can pass WebAuthn credentials and virtual smart cards into Windows Sandbox cleanly.

Understanding Hardware Redirection Directives in WSB

Windows Sandbox operates as a specialized Hyper-V container running lightweight RDP streaming internally. While standard USB pass-through is disabled for isolation security, Windows Sandbox supports virtualized cryptographic security pass-through via smart card and WebAuthn redirection channels.

Authoring the Advanced Security WSB Configuration File

Create an XML configuration file named SecuritySandbox.wsb on your Windows 11 desktop:

<Configuration>
  <VGpu>Enable</VGpu>
  <Networking>Default</Networking>
  <MemoryInMB>6144</MemoryInMB>
  <ClipboardRedirection>Enable</ClipboardRedirection>
  <MappedFolders>
    <MappedFolder>
      <HostFolder>C:AuthTesting</HostFolder>
      <SandboxFolder>C:AuthTesting</SandboxFolder>
      <ReadOnly>true</ReadOnly>
    </MappedFolder>
  </MappedFolders>
  <LogonCommand>
    <Command>powershell.exe -ExecutionPolicy Bypass -Command "Start-Process 'https://webauthn.io' -WindowStyle Maximized"</Command>
  </LogonCommand>
</Configuration>

Enabling Smart Card and WebAuthn Pass-Through in Host Group Policy

To permit Windows Sandbox containers to receive hardware token assertions from the primary Windows 11 host:

1. Press Win + R, type gpedit.msc, and press Enter to launch the Local Group Policy Editor.
2. Navigate to: Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Device and Resource Redirection.
3. Locate Do not allow smart card device redirection and set it to Disabled.
4. Locate Allow WebAuthn redirection and set it to Enabled.
5. Click Apply and restart the Windows Sandbox service or reboot your computer to ensure policy changes take effect.

Verifying WebAuthn and Security Key Authentication

To test hardware key registration inside the sandbox:

1. Insert your FIDO2 / WebAuthn hardware token (such as a YubiKey) into a physical USB port on your host computer.
2. Double-click SecuritySandbox.wsb to launch the configured sandbox session.
3. The automated logon script launches Microsoft Edge and navigates to https://webauthn.io.
4. Click Register. Windows Sandbox invokes Windows Hello / Security Key prompts, passing the cryptographic challenge directly through the virtualized channel to your physical token.
5. Touch the physical security key. The token confirms user presence, completes the cryptographic handshake, and returns a verified registration assertion inside the sandbox environment.