目前 Yahoo! 的研判是 2014 年時由政府單位搬出去的：
A recent investigation by Yahoo has confirmed that a copy of certain user account information was stolen from the company’s network in late 2014 by what it believes is a state-sponsored actor.
這包括了密碼的部份 (受過不同程度的 hash 保護)：
The account information may have included names, email addresses, telephone numbers, dates of birth, hashed passwords (the vast majority with bcrypt) and, in some cases, encrypted or unencrypted security questions and answers.
Based on the ongoing investigation, Yahoo believes that information associated with at least 500 million user accounts was stolen and the investigation has found no evidence that the state-sponsored actor is currently in Yahoo’s network. Yahoo is working closely with law enforcement on this matter.
依照目前在「Have I been pwned? Check if your email has been compromised in a data breach」上的資料，最大的應該是 MySpace 的 3.5 億筆，看起來這次會刷記錄...