Information from a large-scale data breach that impacted Australian travel insurance company Aussie Travel Cover (ATC) in December was leaked online by a teenage hacker. 

ATC was notified of the intrusion on Dec. 23, but failed to immediately notify customers and policy holders, according to the Australian Broadcasting Corporation. The Queensland, Australia-based hacker – known as Abdilo – stole troves of data from two of the company's databases, which contained a total of more than 870,000 personal records. 

The personal data included names and home addresses, in addition to partial credit card numbers. 

The hacker claimed responsibility for the attack via his Twitter handle on Jan. 16 and posted a link to a website containing information from the databases – which has since been removed. ATC and its parent company have issued formal notifications of the data dump on Sunday.