Yahoo data breach
Yahoo data breachReuters

Yahoo on Thursday, September 22, confirmed that it had experienced a massive data breach, in which the credentials of more than 500 million accounts had been stolen by people it suspected were "state actors" -- hackers supported by or working at the behest of other countries.

Althought he breach had taken place in 2014, Yahoo was announcing it only now. The reason behind the delay in announcement is believed to be the former internet giant's deal with Verizon, which agreed to buy its operating business on in July this year for $4.83 billion.

Had the news come out earlier, it could have hurt not only Yahoo's reputation, but also driven down the mount for which Verizon was buying Yahoo, which it plans to merge with AOL to form an entity that could then take on other behemoths in the digital media industry both in the United States and across the world.

Yahoo, in a statement on Friday, said: "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."

It said this state-sponsored actor had stolen the virtual credentials of one user from the company's network in 2014. "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," it said in the statement.

However, financial credentials were not believed to have been stolen. "The ongoing investigation suggests that stolen information did not include unprotected passwords, payment card data, or bank account information; payment card data and bank account information are not stored in the system that the investigation has found to be affected," said Yahoo in the statement.

Yahoo is taking a number of steps to address this situation. Here they are, as listed in the statement:

  • We [Yahoo] are notifying potentially affected users. The content of the email Yahoo is sending to those users will be available at beginning at 11:30 am (PDT).
  • We are asking potentially affected users to promptly change their passwords and adopt alternate means of account verification.
  • We invalidated unencrypted security questions and answers so they cannot be used to access an account.
  • We are recommending that all users who haven't changed their passwords since 2014 do so.
    We continue to enhance our systems that detect and prevent unauthorised access to user accounts.
  • We are working closely with law enforcement on this matter.

Yahoo has also suggested a number of steps for users to find out if their accounts have been compromised, and what to do if that is the case. Here they are, as mentioned in the statement:

  • Change your password and security questions and answers for any other accounts on which you used the same or similar information used for your Yahoo account.
  • Review your accounts for suspicious activity.
  • Be cautious of any unsolicited communications that ask for your personal information or refer you to a web page asking for personal information.
  • Avoid clicking on links or downloading attachments from suspicious emails.

Yahoo also said in the statement: "Additionally, please consider using Yahoo Account Key -- a simple authentication tool that eliminates the need to use a password altogether." Microsoft and other companies have a similar software or mobile apps in place, that help users authenticate any sign-ins to their accounts.