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The Guardian - AU
The Guardian - AU
Josh Taylor

Medibank hackers announce ‘case closed’ and dump huge data file on dark web

a shop front for Australia's largest health insurance company Medibank, in Sydney
A compressed file has been posted on the dark web by cybercriminals behind the Medibank hack, with the size indicating it could contain the remainder of customer data. Photograph: Muhammad Farooq/AFP/Getty Images

The cybercriminals behind the Medibank cyber-attack have posted on the dark web what appears to be the remainder of the customer data they took from the health insurer, stating it is “case closed” for the hack.

On Thursday morning, the blog – which returned online after several days of being offline last week – posted “Happy Cyber Security Day!!! Added folder full. Case closed.” and included a file that has several compressed files amounting to over 5GB.

Guardian Australia has not verified the files, but the file size and the comments on Thursday indicate it could be the full amount of information the hackers took from the Australian health insurer.

The hackers had previously told Medibank in communications prior to the data dump that they were able to extract around 200GB of customer files compressed to 5GB.

Medibank said it is in the process of analysing the data but it “appears to be the data we believed the criminal stole”.

“While our investigation continues there are currently no signs that financial or banking data has been taken,” the spokesperson said. “And the personal data stolen, in itself, is not sufficient to enable identify and financial fraud. The raw data we have analysed today so far is incomplete and hard to understand.”

The Medibank CEO, David Koczkar, unreservedly apologised again to customers, and said it wasn’t “case closed” from Medibank’s perspective.

“We are remaining vigilant and are doing everything we can to ensure our customers are supported. It’s important everyone stays vigilant to any suspicious activity online or over the phone,” he said.

“We will continue to support all people who have been impacted by this crime through our Cyber Response Support Program. This includes mental health and wellbeing support, identity protection and financial hardship measures.”

Call centre hours have been extended and the support team has been increased by more than 300 people. The company has also this week introduced two-factor authentication in contact centres for customers to verify their identity.

The breach covers 9.7 million current and former customers, including 5.1 million Medibank customers, 2.8 million ahm customers and 1.8 million international customers.

The insurer says health claims for about 160,000 Medibank customers, 300,000 ahm customers and 20,000 international customers were accessed. The information exposed includes service provider names and codes associated with diagnosis and procedures.

There were also 5,200 My Home Hospital patients who had their personal and health data accessed, and 2,900 next of kin of these patients who had some contact details accessed.

It is the first drop from the hackers in over a week, and the sixth overall since Medibank refused to pay a US$10m (AU$15m) ransom. The Australian federal police have said the group are located in Russia and are believed to be connected to the REvil ransomware group.

On 20 November the group posted 1,500 records related to claims on chronic conditions such as heart disease, as well as the patient details of people with cancer, dementia, mental health conditions and infections.

Prior to then, 123 customer claims associated with terminating pregnancies, mental health issues, and drug and alcohol use were posted on the blog, along with hundreds of customers’ personal details. Those details include names, addresses, dates of birth, phone numbers, email addresses and gender – but not medical information.

Medibank’s personal information handling practices will now be investigated by the Office of the Australian Information Commissioner, the office announced on Thursday.

The investigation – similar to that already underway with Optus – will look at whether Medibank “took reasonable steps to protect the personal information they held from misuse, interference, loss, unauthorised access, modification or disclosure”.

This week, in response to the Optus and Medibank breaches, the parliament passed legislation that can result in businesses being fined $50m for repeated or serious data breaches.

The prior legislation will apply to Medibank given the breach occurred before the passage of the new legislation, meaning Medibank may face fines of up to $2.2m only for each contravention of privacy if the commissioner seeks penalties from the federal court.

The AFP has said it would seek the assistance of Russian authorities through Interpol to help track down the hackers. It also has a parallel investigation aimed at protecting people whose data has been posted in the hack, by scouring the internet for where the data might be posted and where people may be attempting to profit or scam people from it.

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