I make a sample of Event object to show this issue: How to create a no security level kernel object?
You can do the following operation to set the event in another process
Why I make this sample? Because I want to operate a windows kernel object in the different process, and these process own the different security level. e.g. service and user process. So if you don't set the security descriptor , you will always get the NULL when you invoke OpenEvent API and get the error number is 5.