Cyberattack on Australian telco Optus affects 1.2 million customers

Australian telecoms giant Optus on Monday said personal information and at least one valid form of identification of about 1.2 million customers was compromised in one of the biggest cyber breaches the country has faced.

The breach last month by an anonymous online account, which affected 10 million customers, equivalent to around 40% of Australia's population, attracted harsh criticism from the government.

Late on Monday, Optus said the breach also affected expired IDs and personal information of about 900,000 customers and clarified that "the exposed information did not contain valid or current document ID numbers for some 7.7 million customers".

The company's parent Singapore Telecommunications Ltd (Singtel) said it was assessing the cost of the massive breach at Australia's second-largest telco.

Optus said it has informed the affected customers about the data breach after the Australian government urged it to speed up its notification to 10,200 customers whose personal information were made public.