Yahoo! has revealed it was the target of another security breach.

FOX's Tonya J. Powers has more:

Yahoo! says more than a billion customer accounts were compromised in a security breach and that the breach actually happened back in 2013, but they only recently discovered it.

This is the second data breach disclosure since September. That's when it revealed that 500 million user accounts had been hacked in 2014.

The two attacks are the largest known security breaches of one company's computer networks. Hackers apparently stole passwords in both attacks.

The 2013 attack also involved customer names, phone numbers, birth dates, and security questions. Neither breach has yet been linked to online fraud or any specific repercussions for Yahoo! users.

Tonya J. Powers, FOX News.

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