The Government's spy agency advised Prime Minister John Key not to speculate on who had tried to hack Niwa's Wellington-based supercomputer.
Briefing papers given to Key by the Government Communications Security Bureau (GCSB) on May 24 told him it would be "very unhelpful and premature to speculate on where any potential threat is from".
Two days later, Key announced that the hacking attempt had come from a Chinese IP address, though he added that the true source of the attack could easily be masked.
Correspondence released under the Official Information Act by Science and Innovation Minister Steven Joyce shows the attack was discovered on the evening of May 22, when a systems engineer working on the $12.7 million FitzRoy supercomputer at Greta Point spotted an "anomaly".
Action was taken to combat the attack, and analysis carried out to determine its impact.
Niwa - the National Institute of Water and Atmospheric Research - later said the unauthorised attempt to gain access was unsuccessful.
The computer went back online at 9.48pm on May 25, a heavily censored report from Niwa shows.
The GCSB told Key that specific threats were not usually discussed publicly, to protect vulnerable organisations.
"The priority is the integrity of the infrastructure," the briefing papers show.
An extra briefing provided to Key on May 28 was withheld as it was "likely to prejudice New Zealand's security". The National Cyber Security Centre, part of the GCSB, investigated the incident.
Science and Innovation Minister Steven Joyce said it was appropriate for Niwa to have contacted the NCSC.
"The NCSC will continue to offer support and advise NIWA on cyber security."
Niwa's supercomputer weighs in at 18 tonnes.
- The Dominion Post
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