Minor fixes and Mac > 2 check

SafeExamBrowser.SystemComponents.Contracts/ISystemInfo.cs

@@ -44,13 +44,13 @@ namespace SafeExamBrowser.SystemComponents.Contracts
 		string OperatingSystemInfo { get; }
 
 		/// <summary>
-		/// The MAC Addres of the network addapter
+		/// The MAC address of the network adapter
 		/// </summary>
 		string MacAddress { get; }
 
 		/// <summary>
 		/// Provides the DeviceID information of the user's Plug and Play devices 
 		/// </summary>
-		string[] DeviceId { get; }
+		string[] PlugAndPlayDeviceIds { get; }
 	}
 }

SafeExamBrowser.SystemComponents/SystemInfo.cs

@@ -25,7 +25,7 @@ namespace SafeExamBrowser.SystemComponents
 		public string Name { get; private set; }
 		public OperatingSystem OperatingSystem { get; private set; }
 		public string MacAddress { get; private set; }
-		public string[] DeviceId { get; private set; }
+		public string[] PlugAndPlayDeviceIds { get; private set; }
 
 		public string OperatingSystemInfo
 		{
@@ -133,16 +133,18 @@ namespace SafeExamBrowser.SystemComponents
 		{
 			return Environment.Is64BitOperatingSystem ? "x64" : "x86";
 		}
+
 		private void InitializeMacAddress()
 		{
 			using (var searcher = new ManagementObjectSearcher("Select MACAddress from Win32_NetworkAdapterConfiguration WHERE DNSDomain IS NOT NULL"))
 			using (var results = searcher.Get())
 			{
-				if (results.Count > 0)
+				
+				if (results != null && results.Count > 0)
 				{
-					using (var system = results.Cast<ManagementObject>().First())
+					using (var networkAdapter = results.Cast<ManagementObject>().First())
 					{
-						foreach (var property in system.Properties)
+						foreach (var property in networkAdapter.Properties)
 						{
 
 							if (property.Name.Equals("MACAddress"))
@@ -158,25 +160,27 @@ namespace SafeExamBrowser.SystemComponents
 				}
 			}
 		}
+
 		private void InitializePnPDevices()
 		{
-			List<string> deviceList = new List<string>();
+			var deviceList = new List<string>();
 			using (var searcher = new ManagementObjectSearcher("root\\CIMV2", "SELECT DeviceID FROM Win32_PnPEntity"))
 			using (var results = searcher.Get())
 			{
 				foreach (ManagementObject queryObj in results)
 				{
-					using (queryObj)
+					using (queryObj) 
+					{ 
 						foreach (var property in queryObj.Properties)
 						{
 							if (property.Name.Equals("DeviceID"))
 							{
-								Console.WriteLine(Convert.ToString(property.Value));
 								deviceList.Add(Convert.ToString(property.Value).ToLower());
 							}
 						}
+					}
 				}
-				DeviceId = deviceList.ToArray();
+				PlugAndPlayDeviceIds = deviceList.ToArray();
 
 			}
 		}

SafeExamBrowser.SystemComponents/VirtualMachineDetector.cs

@@ -32,21 +32,25 @@ namespace SafeExamBrowser.SystemComponents
 			var manufacturer = systemInfo.Manufacturer.ToLower();
 			var model = systemInfo.Model.ToLower();
 			var macAddress = systemInfo.MacAddress;
-			var deviceId = systemInfo.DeviceId;
+			var plugAndPlayDeviceIds = systemInfo.PlugAndPlayDeviceIds;
-			
+
 			isVirtualMachine |= manufacturer.Contains("microsoft corporation") && !model.Contains("surface");
 			isVirtualMachine |= manufacturer.Contains("vmware");
 			isVirtualMachine |= manufacturer.Contains("parallels software");
 			isVirtualMachine |= model.Contains("virtualbox");
 			isVirtualMachine |= manufacturer.Contains("qemu");
-			
+
-			isVirtualMachine |= ((byte.Parse(macAddress[1].ToString(), NumberStyles.HexNumber) & 2) == 2 || macAddress.StartsWith("080027"));
+			if (macAddress != null && macAddress.Count() > 2)
-			
+			{
-			foreach (var device in deviceId)
+				isVirtualMachine |= ((byte.Parse(macAddress[1].ToString(), NumberStyles.HexNumber) & 2) == 2 || macAddress.StartsWith("080027"));
+			}
+
+			foreach (var device in plugAndPlayDeviceIds)
 			{
 				isVirtualMachine |= PCI_VENDOR_BLACKLIST.Any(device.ToLower().Contains);
 
 			}
+
 			logger.Debug($"Computer '{systemInfo.Name}' appears to {(isVirtualMachine ? "" : "not ")}be a virtual machine.");
 
 			return isVirtualMachine;