That's the dire scenario Home Affairs boss Michael Pezzullo has warned politicians about unless security agencies are given more powers to fight cyber attacks on critical infrastructure.

A bill to give national security agencies powers to intervene in some companies' networks to block major risks is before federal parliament.

Mr Pezzullo said the situation was perilous, describing the risk level as deeply concerning,

"COVID's been dreadful. COVID's been terrible given the deaths. Imagine trying to do COVID without electricity," he told a Senate committee in Canberra on Monday.

"It's as immediate, it's as realistic and it's as credible a threat as that."

Parliament's powerful intelligence and security committee is considering the legislation, which the government wants passed by the end of next month.

Mr Pezzullo said international criminal groups and state-based actors were already threatening hospitals and vaccine data in Australia.

He said while cyber attacks on businesses were common, there were major risks for the nation's critical health, finance and fuel pipeline infrastructure.

"It's a pressing, urgent problem," Mr Pezzullo said.

Under the draft laws, companies operating hospitals, communications networks, electricity, transport, banking, food supplies and defence, would face more stringent reporting obligations.

Mr Pezzullo said more connectivity across critical infrastructure made business sense but also left Australia more vulnerable to attacks.

"We're seeing this with hospital systems, we're seeing it with vaccine data, we're seeing it with healthcare providers," he said.

"Cyber criminals tend to be very business savvy so they'll chase opportunity. Typically the more critical a system, the more critical a data set, the more the critical opportunity there might be.

"That's before you get to state actors and there's a combination effect of state actors working with criminal actors."

Australian Associated Press