New Zealand’s top level security apparatus has been gathered to defend against ongoing cyberattacks, which have now afflicted the country's security agencies.

Government officials that make up ODESC (Officials' Committee for Domestic and External Security Coordination) met on Friday to discuss the cyberattacks, which last week crashed the stock exchange NZX’s website and forced it to at times halt trading.

ODESC is headed by government chief executives and is the primary committee of the National Security System, which swings into action during crises that threaten New Zealand’s security, sovereignty or economy. The committee was previously stood up to respond to the Covid-19 pandemic, and convened in the hours after the March 15 terror attack in 2019.

The distributed denial of service (DDoS​) cyber attacks, launched from overseas, have since extended to New Zealand’s security agencies, including the Government Communications Security Bureau (GCSB).

The GCSB and New Zealand Intelligence Community websites were briefly offline on Tuesday afternoon when Stuff tried to access them.

Minister for the security agencies Andrew Little said it was “hard to know” whether the attacks were increasing, but the attacks on the NZX had justified calling together ODESC.

Little, who was getting daily briefings on the attacks, said NZX had been stable on Tuesday, however the GCSB had notified him that it had been targetted.

Another incident had been reported by the TSB Bank, which alerted authorities to a disruption in its services, as well as Kiwibank, on Tuesday. It appears other banks have been targetted, and media companies Stuff and Radio NZ have also fended off attacks.

• Stuff, RNZ say they were the target of a failed cyberattack
• NZX website goes down yet again
• Govt spy agency has 'no clues' on source of cyberattacks on NZX
• NZX boss tight lipped on cause of cyber attacks

“The level of threat is no greater today than it was in the middle of last week,” Little said.

"The risk is there, and we know internationally these attacks are ongoing, and while the incidence of it is reasonably high at the moment there is a risk. But equally, a lot of organisations have got the measures in place to withstand an attack.”

Little said the GCSB was leading ODESC on this occasion, and the prime minister had asked him to be the minister responsible for the response.

The Department of Prime Minister and Cabinet acts as co-ordinator of ODESC, and routine its membership includes the State Services Commission, Treasury, Ministry of Foreign Affairs and Trade, the Defence Force and the police.

Also at the table on this occasion was the Ministry of Business, Innovation and Employment, and the Department of Internal Affairs, due them having digital communication networks, Little said.

"It's really just assuring that whatever effort is required from any part of government is harnessed and put in motion where that is needed ... They were satisfied that everything that needed to be in place was in place,” Little said.

The GCSB did not respond to requests for comment.

A DDoS attack crashes a website by intentionally overloading it with more traffic than it can handle.

The identity of the cyber attackers remain unknown, Little said. In some instances the attackers had demanded a ransom payable in cryptocurrency Bitcoin.