ANU vice-chancellor Brian Schmidt noted the report found less information was taken than initially feared but said he was still"stunned"by the incident and apologised to students,staff and alumni.
"This wasn't a smash and grab. It was a diamond heist. It was an extremely sophisticated operation,most likely carried out by a team of between five to 15 people working around the clock,"Professor Schmidt said.
He said the release of extensive report was an act of"radical transparency"to make sure he was accountable to the people affected and to encourage a stronger and more open culture around cyber security.
China has beenreported as the prime suspect in the attack,with intelligence officials fearing the data stolen could be used to compromise university alumni pursuing careers with the Australian government,including in sensitive national security roles.
When the hack waspublicly revealed in June,the ANU warned that 19 years worth of personal data covering 200,000 staff and students may have been compromised but it has now downplayed the impact,saying the hackers may have failed to achieve their objective.
"More recent forensic analysis has been able to determine that the amount of data taken is much less than 19 years'worth;although it is not possible to determine how many,or precisely which,records were taken,"the report states.