A former Yahoo executive claims that between one billion and three billion user accounts could have been impacted by the Yahoo data hack.
The Yahoo data breach, according to the experts from the intelligence firm InfoArmor that looked into the event, is the consequence of a cyberattack carried out by cybercriminals who later sold the Yahoo user accounts to a nation-state actor from Eastern Europe.
InfoArmor experts verified that the initial hacker to offer the massive data dump for sale is a threat actor going by the handle tessa88; he served as a go-between for the real criminals.
A former Yahoo executive, speaking anonymously, claims that the Yahoo architecture collects all user authentication data into a single database.
Source: https://securityaffairs.com/51833/data-breach/yahoo-data-breach-2.html
"id": "YAH203551123",
"linkid": "yahoo",
"type": "Breach",
"date": "10/2014",
"severity": "100",
"impact": "5",
"explanation": "Attack threatening the organization’s existence"