Shield.cs

BitmapSource shieldSource = null;

if (Environment.OSVersion.Version.Major >= 6)
{
    SHSTOCKICONINFO sii = new SHSTOCKICONINFO();
    sii.cbSize = (UInt32) Marshal.SizeOf(typeof(SHSTOCKICONINFO));

    Marshal.ThrowExceptionForHR(SHGetStockIconInfo(SHSTOCKICONID.SIID_SHIELD,
        SHGSI.SHGSI_ICON | SHGSI.SHGSI_SMALLICON,
        ref sii));

    shieldSource = System.Windows.Interop.Imaging.CreateBitmapSourceFromHIcon(
        sii.hIcon,
        Int32Rect.Empty, 
        BitmapSizeOptions.FromEmptyOptions());

    DestroyIcon(sii.hIcon);
}
else
{
    shieldSource = System.Windows.Interop.Imaging.CreateBitmapSourceFromHIcon(
        System.Drawing.SystemIcons.Shield.Handle,
        Int32Rect.Empty, 
        BitmapSizeOptions.FromEmptyOptions());
}