NEW DELHI: Efforts to recreate the Big Bang theory at Cern hit its first roadblock, with scientists admitting that their experiment was hacked into by maverick hackers. ( Watch ) The hackers reportedly mounted an attack on the Large Hadron Collider, which has raised eyebrows over the security of this historic experiment in the world, as it surpasses a vital milestone. Scientists say that it was a competition between two hacker groups - known in hacking circles as 2600 and 1337, that led them to break into the experiment just before it was to begin. 2600, also known as the Greek Security Team broke into the experiment and left a message saying, "We are 2600.. don't mess with us..." The scientists who were behind the mammoth experiment had received threatening emails prior to the start. No real damage done, but the hackers got perilously close. The hackers attacked the Compact Muon Solenoid Experiment, or CMS. Scientists working at Cern, the organisation that runs the vast smasher, were worried about what the hackers could do because they 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. If they had hacked into a second computer network, they could have turned off parts of the vast detector and, said the insider, "it is hard enough to make these things work if no one is messing with it." Fortunately, only one file was damaged but one of the scientists firing off emails as the CMS team fought off the hackers said it was a "scary experience". The hackers breached the CMSMON system, which monitors the CMS software system. CMS takes vast amounts of data during collisions.