Web security expert Troy Hunt said not every system would be back up and running.

“There’s lots of companies that won’t have full restoration services, in part because a lot of organisations have a very large number of different machines across their inventory,” he said. “Then you’ve got organisations with satellite offices in different locations.”

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“I’m sure we will see a detailed post-mortem from CrowdStrike – they’re the sort of company I think will be quite transparent about this … perhaps inhibiting that is that they’re going to get smashed with lawsuits after this. I’m sure that everything they say will be going through many lawyers beforehand.”

Australian Chamber of Commerce and Industry chief executive Andrew McKellar said there was “no doubt” the outage had cost businesses a lot of money.

“We have to hope that most businesses can weather that sort of impact over a one, two, three-day period,” McKellar said on Sunday. “Its timing couldn’t have been worse, in particular on a Friday afternoon. It’s meant many businesses are going to have to wait until early [this] week to put in place the fixes they need.”

Shadow Treasurer Angus Taylor said the incident had reinforced the concerns of having large amounts of internet systems in the hands of a few firms.

“It’s also very clear that government and businesses have got to get smarter and better at being able to deal with these situations,” he told Sky News.

“That might mean having redundancy, it might mean ensuring that you’ve got alternatives, it certainly might mean not having one organisation or one company with too much market share.”

The Business Council had been working with government agencies and industry following the outage, chief executive Bran Black said.

“With major services back online, the main concern now is the potential for further disruption as people return to work tomorrow and identify issues as they attempt to log into their systems,” he said.

“Some delays are still occurring through supply chains and a request has been made for truck delivery curfews to be eased for a week to allow supplies to be re-stocked.

“The BCA is concerned by an increase in phishing and scam activity and is urging people to be cautious and continue to listen to official advice.”

Assistant Energy Minister Jenny McAllister said work was ongoing between the government and sectors hit by the outage to ensure they were up and running.

“We are still in recovery stage ... there is still more work to do to make sure that the residual issues arising from this outage are able to be addressed,” she told Sky News on Sunday.

“There will be opportunity in time to reflect on what’s occurred over the last couple of days, whether it exposes vulnerabilities that we are able to address.

“The key thing at the moment, and the focus for the government, is restoring services.”

With AAP

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