Yahoo Data Breach, the company confirms the incident that exposed 500M accounts

The announcement about the Yahoo data breach is online, the company confirmed that hackers managed to access data from at least 500 million user accounts.

Today I wrote about the imminent announce of the Yahoo data breach related to an incident that resulted in the leakage of 200 million Yahoo account credentials this summer.

The company has finally made the announce, the news related the Yahoo data breach is in the headlines. The IT giant confirmed that hackers have stolen at least 500 million user accounts in a data breach dating back to 2014.

Yahoo also added that its security experts suspect the involvement of nation-state actors.

“We have 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. 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.” reads the security notice issued by Yahoo.

“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. 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.”

This summer the notorious hacker Peace advertised 200 Million Yahoo accounts on Dark Web, and the company was aware of the sale.

Peace offered for sale the 200 million of Yahoo account credentials (from “2012 most likely,”) on The Real Deal black marketplace. Yahoo was informed of the events and launched an internal investigation avoiding public comment on the case. The hacker was offering the data leak for 3 bitcoins (roughly $1,800 at the time of the disclosure).

The security notice informs users that the company is taking the necessary action to protect them. Below the list published by Yahoo:

• We are notifying potentially affected users. The content of the email Yahoo is sending to those users will be available at https://yahoo.com/security-notice-content 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 unauthorized access to user accounts.
• We are working closely with law enforcement on this matter.

We encourage our users to follow these security recommendations:

• 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 is encouraging users to use the Yahoo Account Key in order to definitively eliminates the need to use a password.

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Pierluigi Paganini

(Security Affairs – Data Breach, Yahoo Data Breach)