28/06/2017 12:01 PM AEST | Updated 28/06/2017 1:45 PM AEST

Global Cyber Attack Reaches Australia, Shuts Down Cadbury Factory

The attack has caused havoc in Russia, Ukraine and the United States.

A global ransomware attack which on Tuesday took out servers at Russia's largest oil company and disrupted Ukraine's banks has reached Australia.

The Cadbury chocolate factory in Tasmania was the first Australian company to be hit, with the 'Petya' malware bringing down its IT systems at around 9:30pm on Tuesday night.

Some employees were reportedly sent home from work on Wednesday morning, as operations were forced to a halt.

International law firm DLA Piper's Australian office was in shut-down on Wednesday morning as the company dealt with "a serious global cyber incident".

"We have taken down our systems as a precautionary measure which will mean you are currently unable to contact us by email or landline," the law firm advised clients on its website.

Local staff were informed via text early on Wednesday morning that IT systems had been shut down to contain the situation, according to the ABC.

Australian staff at Reckitt Benckiser -- which produces health and hygiene products including Nurofen, Dettol, Durex and Air Wick -- have also reportedly been sent home from work as the company systems are under attack.

The ransomware works by infecting computers within a network, before spreading via the internet. Computers infected by the malware display a distinctive black screen with red text instructing the user to pay a ransom of $300 worth of bitcoin in order to unlock their computer.

Russia and Ukraine were the first to be affected by the attacks on Tuesday, which quickly spread to the rest of Europe and then around the world.

Experts have said this ransomware is likely to be worse than the Wannacry attack, which hit more than 30,000 computers in May, but companies were likely to be better protected.

The Wannacry attack is still having flow-on effects in Australia, including leading Victoria Police on Monday to suspend 590 speed and traffic offences, after the ransomware was found to have infected nearly 100 road safety cameras.

The new strain of virus has similarities to a well-known software called Petya but may be a modified or wholly new version, according to the Sydney Morning Herald.

Special Adviser to the Prime Minister on Cyber Security, Alastair MacGibbon, said that the ransomware will spread through networks in the same way as Wannacry did last month.

"Then it will jump out onto the internet, and it will look for other victim computers... that have particular vulnerability," he said.

"The best protection is to patch your operating system, your Windows operating system, and make sure you back up your files."

MacGibbon also warned users who had been infected not to pay the ransom.

"Our advice is you don't ever pay a criminal... There's no knowledge that they will actually unlock the system. The best protection against ransomware is to make sure you don't pay the criminals by not being infected."

MacGibbon said the Wannacry attack last month was "a wake up call" of the potential of such attacks to wreck havoc on a global scale.

"This is another example of how connected we are, and why we need that discipline in patching and backing up," he said.

The Australian Signals Directorate is working with the government to ensure government agencies' systems have adequate protections.