Australia's top health insurer reels after data breach

An illuminated sign is seen outside a branch of the Australian health insurer Medibank Private in Sydney October 20, 2014. REUTERS/David Gray

Nov 7 (Reuters) - Medibank Private Ltd (MPL.AX), Australia's biggest health insurer, reported a massive data breach in October that compromised personal and medical information of its current and former customers, and slashed its stock value by almost a fifth.

The incident was one among a recent slew of hacks into some of the country's largest companies, which experts say points partly to an understaffed and overworked cybersecurity workforce. read more

Here is what we know of the Medibank incident so far:

Oct. 13: Medibank says it detected unusual activity on its network and removes access to some customer-facing systems. The company says there was no evidence that any sensitive data was accessed. read more

Oct. 17: Normal business operations resume. Medibank reaffirms there was no evidence that customer data had been removed from its network. read more

Oct. 19: Medibank says an unnamed hacker group contacted it to negotiate about customer data it claimed to have retrieved from the company's IT systems. read more

Oct. 20: Medibank confirms that a criminal stole personal information of 100 customers, including medical diagnoses and procedures, as part of a theft of 200 gigabytes of data. read more

Oct. 21: Medibank suspends trading amid the likelihood that the hack may impact more customers.

Oct. 25: The insurer says policy records of a further 1,000 customers were stolen by the criminal and that the number would likely rise. read more read more

Oct. 26: Medibank says the hack compromised data of all of its nearly 4 million customers, flags a potential charge of up to A$35 million ($22.4 million) for the first half, and withdraws fiscal 2023 forecast for a key growth metric. read more

Nov. 7: Medibank says no ransom will be paid to the criminal responsible for the data theft and that data of around 9.7 million current and former customers was compromised. read more

($1 = 1.5632 Australian dollars)

Compiled by Upasana Singh in Bengaluru; Editing by Rashmi Aich

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