According to reports the hack attack on the lab, which carries out research into high-energy physics, sparked a national alert, resulting in the arrest of McElroy, aged 18, in July 2003.
McElroy admitted to police that he had carried out the attack, but said that he had thought that he was hacking into a university computer system. He and a group of other hackers had developed means of hacking into such networks in order to store their digital music and film files, says a report in ComputerWeekly.com.
National security was not affected by the attack, although the lab system had to close for three days to allow repairs to be carried out – at a cost of £20,000. The data held on the system was unaffected, according to the report.
McElroy is due to be sentenced by Bow Street Magistrates Court on 21st November.