Law firm Slater and Gordon has confirmed it is investigating a potential class action after the personal information of millions of Australians was compromised in last week's massive Optus breach.
It comes as Optus pledged to offer free credit monitoring today to its "most affected" customers, following a call to action by Home Affairs Minister Clare O'Neil.
The data of more than nine million Optus current and former customers was compromised during the breach last week, the perpetrators of which remain unknown.
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Slater and Gordon class actions senior associate Ben Zocco said the firm was assessing possible legal options for affected customers.
"This is potentially the most serious privacy breach in Australian history, both in terms of the number of affected people and the nature of the information disclosed," Zocco said.
"We consider that the consequences could be particularly serious for vulnerable members of society, such as domestic violence survivors, victims of stalking and other threatening behaviour, and people who are seeking or have previously sought asylum in Australia."
Meanwhile, O'Neil said in Question Time that such a massive breach should not have been expected from a major telco.
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She said the government was working on steps to be taken to protect Australians against future attacks, noting the legal nature of the process was highly complex.
"One significant question is whether the cyber security requirements we place our large telecommunications providers in this country are fit for purpose," she said.
"I also note that in other jurisdictions, a data breach of this size will result in fines amounting to hundreds of millions of dollars."
Optus, meanwhile, has offered free credit monitoring to customers, issuing a statement shortly after O'Neil called for just that action to be taken.
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"Optus is offering the most affected current and former customers whose information was compromised because of a cyberattack the option to take up a 12-month subscription to Equifax Protect at no cost," it said in a statement.
"Equifax Protect is a credit monitoring and identity protection service that can help reduce the risk of identity theft.
"The most affected customers will be receiving direct communications from Optus over the coming days on how to start their subscription at no cost. Please note that no communications from Optus relating to this incident will include any links as we recognise there are criminals who will be using this incident to conduct phishing scams."
The statement does not, however, say what constitutes a "most affected customer".
Optus still contacting affected customers
The telco issued a statement this morning to say it had sent "email or SMS messages" to all customers whose ID document numbers, such as their licence or passport number, were compromised.
"We continue to reach out to customers who have had other details, such as their email address, illegally accessed," Optus said in a statement.
"We understand and apologise for the concern that this has caused for our customers."
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Payment details and account passwords have not been compromised, Optus said.
In a letter issued to affected customers, Optus offered advice on what to do next.
"Look out for any suspicious or unexpected activity across your online accounts, including your bank accounts. Make sure to report any fraudulent activity immediately to the related provider," the letter read.
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People are also advised to beware contact from scammers, to avoid suspicious links, and to not provide computer access to anybody who calls, though they may claim to be from a reputable organisation.
In the letter, Optus also said it chose to reveal the hack via the media as it was deemed to be the quickest and simplest way of reaching the most customers, with individual contact to follow.
Prime Minister Anthony Albanese said today on 4BC the cyber-attack was a "huge wake-up call" for the corporate sector.
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"We want to make sure, as well, that we change some of the privacy provisions there so that if people are caught up like this, the banks can be let known, so that they can protect their customers as well," he said.
"We know that in today's world, there are actors, some state actors, but also some criminal organisations who want to get access to people's data."
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