At least a dozen Australian businesses have been crippled by the malicious ransomware computer bug that has claimed more than 200,000 victims around the world.
The federal government has confirmed 12 reported cases in Australia of the 'WannaCry' software.
Four private businesses in Darwin and Alice Springs have suffered "significant impact", Northern Territory Police said, with some still prevented from operating.
The government wouldn't reveal details of the other affected businesses.
Some experts believe the ransomware - which blocks access to data until a ransom is paid - has links to North Korea.
"The ransomware incident highlights the need for all businesses to ensure that their systems are up-to-date with the most current patches and they have back-up procedures in place," Detective Sergeant Craig Windebank said.
"If your computer system has the most recent patches installed, you are safe from this incident."
But a majority of Australian companies admit they're not sure how to protect unorganised data from being stolen, research shows.
The research shows about half of Australian organisations suffered two or more security breaches in the past 12 months, costing an average of $1.8 million.
Almost two-thirds expect to be breached again this year.
The study surveyed 600 companies globally - including 50 local businesses - with at least 1000 employees.
It found 66 per cent of Australian firms weren't sure how to manage and protect unstructured data - unorganised, text-heavy material - from potential theft.
Employees who don't stick to security policies are proving a headache, as well as risks posed by vendors and contractors.
Only 26 per cent of respondents said they have the ability to provide a report of "who has access to what" within 24 hours - lower than the 33 per cent global average.
The research was commissioned by identity management company SailPoint.
