__InstanceCreationEvent TargetInstance properties all null

Question

I'm trying to use WMI events to monitor process which are started on the local computer. I use the following code to test the event and monitor for processes:

class Program
{
    static void Main(string[] args)
    {
        ManagementEventWatcher watcher = WatchForProcessStart();
        while(true) watcher.WaitForNextEvent();
    }

    private static ManagementEventWatcher WatchForProcessStart()
    {
        string scope = @"\\.\root\CIMV2";
        string queryString = "SELECT TargetInstance FROM __InstanceCreationEvent WITHIN 10 WHERE TargetInstance ISA 'Win32_Process'";

        ManagementEventWatcher watcher = new ManagementEventWatcher(scope, queryString);
        watcher.EventArrived += ProcessStarted;
        watcher.Start();
        return watcher;
    }

    private static void ProcessStarted(object sender, EventArrivedEventArgs e)
    {
        ManagementBaseObject targetInstance = (ManagementBaseObject)e.NewEvent.Properties["TargetInstance"].Value;
        targetInstance.Properties.Cast<PropertyData>().ToList().ForEach(p => Console.WriteLine("{0}={1}", p.Name, p.Value));
    }
}

However the TargetInstance propeties are all present but have a value of null when I start a process. Any ideas?

Answer 1

You are getting null values because you are not retrieving the fields in the WQL sentence-

replace this

  string queryString = "SELECT TargetInstance FROM __InstanceCreationEvent WITHIN 10 WHERE TargetInstance ISA 'Win32_Process'";

by this

  string queryString = "SELECT * FROM __InstanceCreationEvent WITHIN 10 WHERE TargetInstance ISA 'Win32_Process'";