StuxNet was designed to change motor frequencies on nuclear enrichment facilities to destroy them, if you drag Flame and StuxNet down it's a code, in this code Flame is far more complex flame can sense virus scanning software's and edit itself to become fit for it in terms of size StuxNet is 568Kb and Flame is 20 Mb. And flame's true potential is that of unknown, 20Mb's of code just to steal info is a bit strange it would take about 10 years to decode it all and figure it out so, it's not very well known.