A survey of more than 13,000 people by the Australian Institute of Criminology found 47 per cent reported some impact from cyber crime in the past year.
More than a quarter had been the victim of online abuse and harassment.
Unsolicited sexually explicit messages, images or videos were the most common form reported by one in 10 users.
Australia was hit with several major data breaches with hackers stealing the personal details of millions of Optus, Medibank and Latitude Financial customers in the past nine months.
One in three survey respondents said their information had been exposed in a data breach while one in five were impacted by identity crime and misuse.
The institute's Anthony Morgan said most people don't report being a victim of cyber crime and official statistics significantly underestimate the extent of the impact.
"While many people don't report because they think they could deal with the problem themselves or because it wasn't serious enough, a large proportion didn't know where or how to report," Mr Morgan said.
About half of all incidents reported to authorities were investigated, but perpetrators were only apprehended in one in 20 incidents.
Twenty-two per cent of computer users reported being victims of malware with pop-up ads the number one issue.
Frauds and scams netted about eight per cent of surveyed users with online shopping scams the most common crime.
Those who spent more time online were more likely to be victims of cyber crimes with younger people more susceptible than their older counterparts.
Men were more likely to fall victim to fraud and scams and online abuse, and LGBTQI people were significantly more likely than heterosexual respondents to have been a victim of online abuse and harassment and malware.
Those who spoke a language other than English at home were more likely to be impacted by malware, identity crime and misuse, and scams and fraud.
The federal government has appointed Air Vice-Marshal Darren Goldie as Australia's first national cyber security coordinator.
He will bring together national security policy, responses to major incidents and whole-of-government preparedness.
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