The Australian Federal Police has launched an operation to protect more than 10,000 Optus data breach victims whose details were leaked online, as cyber investigators try to identify those responsible.
That announcement comes as Prime Minster Anthony Albanese said Optus had confirmed to him it would cover the costs of replacement passports for all customers affected by the breach.
Around 10 million current and former Optus customers had their personal details stolen, including drivers licence and passport numbers, in a breach last week.
The hacker released the personal details of more than 10,000 people on an online forum, before removing the post.
On Friday, the AFP announced it was working with state and territory police to identify the affected individuals and was monitoring the dark web and online forums for other bad actors who may have grabbed the information before it was removed.
Justine Gough, Assistant Commissioner for cyber command at the AFP, said the customers affected by the breach would receive "multi-jurisdictional and multi-layered protection from identity crime and financial fraud".
"The 10,000 individuals who potentially had 100 points of identification released online will be prioritised," Assistant Commissioner Gough said.
"Cyber crime is the break-and-enter of the 21st century and we encourage all Australians to be extra vigilant about their online security at this time."
Banks, international law enforcement assist investigation
The AFP will also engage with the financial services industry to detect criminal activity associated with the breach.
Assistant Commissioner Gough said cyber investigators were following multiple leads as they attempted to track down the person or people behind the breach.
"We expect it to be long and complex," she said.
"The cyber criminal behind this attack has used obfuscation techniques to conceal their identity, their location and their activity."
Assistant Commissioner Gough said the AFP was collaborating with international law enforcement, including the FBI.
"We are talking about a type of crime that is borderless," she said.
She said Optus was cooperating with the investigation.
The AFP is advising people to not click on links in emails and text messages purporting to be from Optus, and to instead contact the telco through its official channels.
On Friday, Mr Albanese said that Optus had told him it would pay the fees for replacing passports for those caught up in the breach.
"Optus have responded to my request that I made both in the parliament and that Senator Wong made in writing to Optus, they will cover the costs of replacing affected customers passports," he said.
"I think that's entirely appropriate."