Define "security". What problem do you have that you are trying to fix?
If you want to be able to administer quizzes and be absolutely sure that the person you think should be doing the quiz is doing it then you need to do it under exam conditions. There is loads and loads of discussion on the Interweb about this. It's most certainly not something you can "just fix" in Moodle.
If people want to cheat, they will cheat.