Yahoo Inc warned that it had uncovered yet another massive cyber-attack, saying data from more than 1 billion user accounts was compromised in August 2013, making it the largest breach in history.
According to New York Times, the newly disclosed 2013 attack involved sensitive user information, including names, telephone numbers, dates of birth, encrypted passwords and unencrypted security questions that could be used to reset a password.
Reuters reports that the number of affected accounts was double the number implicated in a 2014 breach that the internet company disclosed in September and blamed on hackers working on behalf of a government.
News of that attack, which affected at least 500 million accounts, prompted Verizon Communication Inc to say in October that it might withdraw from an agreement to buy Yahoo’s core internet business for $4.83 billion. The internet company has more than 1 billion active users, but it is not clear how many inactive accounts were hacked.
The breach is the latest setback for Yahoo, an internet pioneer that has fallen on hard times in recent years after being eclipsed by younger, fast-growing rivals including Alphabet Inc’s Google and Facebook Inc.