It said the attackers may have gained access to claims data, including clinical information, along with banking account numbers, Social Security numbers, birth dates and other data in an attack that began in May 2014.
About 6 million of the people whose accounts were accessed are residents of Washington state, where customers include employees of Amazon.com, Microsoft and Starbucks, according to Premera. The rest are scattered across every state in the US.
Medical records are highly valuable on underground criminal exchanges where stolen data is sold because the information is not only highly confidential, it can also be used to engage in insurance fraud.
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