Yahoo revealed that a 2013 security breach it discovered last year affected all 3 billion user accounts the company had at that time.
Yahoo in December 2016 disclosed that data associated with more than 1 billion user accounts was stolen in August 2013. In September 2016, the company reported a separate breach, confirming that data linked with at least 500 million user accounts was stolen from its network in late 2014.
The operating business of Yahoo was acquired by Verizon Communications Inc. earlier this year in a deal worth about $4.48 billion. Verizon had negotiated to reduce the original deal price by $350 million after Yahoo disclosed the data breaches. After the acquisition, Verizon combined the acquired assets of Yahoo with its AOL business to create a new subsidiary called Oath.
Following the acquisition, and during integration, the company obtained new intelligence after an investigation with the help of outside forensic experts and now believes all Yahoo user accounts were affected by the August 2013 theft, according to an Oct. 3 news release. The company said the hacked information did not include "passwords in clear text, payment card data, or bank account information."