SAN FRANCISCO — Yahoo, already reeling from its September disclosure that 500 million user accounts had been hacked in 2014, disclosed Wednesday that a different attack a year prior to the previously announced hack; this time more than 1 billion accounts were compromised.
The hack occurred in August of 2013. Yahoo! reports that the stolen data included users’ names, email addresses, telephone numbers, dates of birth, and in some cases, encrypted passwords. Those passwords are MD5 encrypted, which experts believe is possible to crack with time and patience. The hacked data also includes some security questions and answers, some of which were not encrypted.
This second larger breach is a black eye for Chief Executive Marissa Mayer, a former Google exec., who joined Yahoo in 2012 with a mission to turn around the tech giant which was not thought by many to doing well in the smartphone era.
It is unknown how many Yahoo users were affected by both the 2013 and 2014 attacks. The internet company has more than 1 billion active users, but it is not clear how many inactive accounts were in the hacked data.
Investors appeared worried about the Verizon deal. Yahoo’s shares fell 96 cents, or 2 percent, to $39.95 after the disclosure of the latest hack.