More than 60,000 Victorian motorists caught at virus-infected red light and speed cameras will now have to pay their fines.
Police and Road Safety Camera Commissioner John Voyage says the WannaCry virus, which infected 160 cameras but has since been cleared from the system, did not compromise any data.
"We can say with confidence that there is no breach of the integrity of the data. There is no compromise of the system," he told reporters on Friday after a preliminary investigation.
"Nobody who has obeyed the law will receive an inappropriate infringement."
A contractor inadvertently uploaded the ransomware virus onto the network on June 6 while using a USB stick for a system update.
The virus infected cameras operated by Redflex and Jenoptik before all systems were patched on June 22.
About 61,000 fines suspended or withdrawn during a preliminary investigation into the integrity of the cameras will be reissued, Victoria Police confirmed.
"All the fixed speed and red light cameras were working correctly from June 6 to 22, and... all detections throughout the fixed camera network are valid," a police spokeswoman said in a statement.
Mr Voyage said he will investigate how the virus got into the system.
"The virus is known to have attempted to attack the system. It has spread in the system, which should have been a secure system," Commission Voyage said.
"But it did not actually take the second step of encrypting."
Police Minister Lisa Neville learned about the virus in late June, when it was reported publicly in the media.
On Friday she said she was "extremely disappointed" the companies appeared to have not taken the virus as seriously as they should.