Singtel-owned Optus named Deloitte to conduct an independent external review of its security systems and controls following a recent cyberattack which impacted up to 9 million customers.

The international professional services company will conduct a forensic assessment of the cyberattack and the circumstances surrounding the incident, which led to unauthorised access of current and former customers’ information including names, birth dates, confidential ID documents and email addresses.

Optus stated its board fully backed a call for the review made by CEO Kelly Bayer Rosmarin.

Rosmarin said the review would play a crucial role in the operator’s response to the attack.

“We’re deeply sorry that this has happened and we recognise the significant concern it has caused many people. While our overwhelming focus remains on protecting our customers and minimising the harm that might come from the theft of their information, we are determined to find out what went wrong.”

“This review will help ensure we understand how it occurred and how we can prevent it from occurring again.”