"Shortly after physicists activated the Collider on Wednesday, hackers identifying themselves as Group 2600 of the Greek Security Team accessed computers connected to the Compact Muon Solenoid detector, one of four key subsystems responsible for monitoring the collisions of protons speeding around the 18-mile track near Geneva, Switzerland.
A few scientists had worried that the experiment could inadvertently create a planet-swallowing black hole. Physicists called this impossible, or at least extraordinarily unlikely. But the hack raises a different sort of worst-case scenario: the largest and most complicated science experiment in history, intended to reveal basic information about the composition of matter, derailed by malevolent intruders."
According to the Telegraph, the hackers were "one step away" from the computer control system of one of the huge detectors of the machine, a vast magnet that weighs 12,500 tons, measuring around 21 metres in length and 15 metres wide/high.
Fun as it might be to speculate on whether hackers could have generated The End of the World (movie rights opending, surely) it's very clear that the worst that could have been done would have been the derailing or contamination of the experiemental results. But considering that £4.4 billion was spent on the LHC, even that would have been somewhat more serious than hax0r tricks.
If the US wants to sentence Gary McKinnon to life, what would they do to these guys if they get hold of them? Luckily for them if they ever get caught, the jurisdiction would presumably fall to the Swiss or Greek courts!