Optus has revised the number of its customers whose Medicare card numbers were exposed in a recent data breach to 43,000.
Last Sunday, minister for government services Bill Shorten put the number of Medicare numbers exposed at “about 36,900”.
In an update posted today, Optus said 17,000 current Medicare card numbers and 26,000 expired card numbers were exposed.
“Optus can confirm that we have communicated with all contactable customers who have had their Medicare card number exposed”, the carrier said.
News of the data breach, which Optus says exposed 9.8 million customer records, first emerged two weeks ago.
The discovery comes a day after the government announced temporary telecommunications regulations designed to help identify people whose information was involved in the breach.
A small subset of the breached records was briefly published on a hacker forum, and the Australian Federal Police has accused a 19-year-old from Rockdale in Sydney of trying to blackmail people from that list into paying him $2000.
The police are still seeking whoever was responsible for the original hack.