While all of this information could have been exposed to hackers, the company isn't sure exactly what may have been revealed. The investigation thus far hasn't shown any evidence of what data was stolen and whether it was used in any nefarious way, but Excellus is still offering its customers the now-commonplace two years of free credit monitoring and identity theft protection.

Unfortunately, hacks against healthcare providers are hardly a rarity at this point. An attack on Premera, another arm of BlueCross, was revealed in March of this year, putting the data of 11 million customers at risk. And just a month earlier, Anthem was hacked -- the database accessed in that breach contained the info of a whopping 80 million customers, though only a portion of those were believed to have been accessed.

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