Yahoo says hackers stole data from over one billion accounts

Yahoo announced that hackers stole data from over one billion accounts in 2013. According to the company, the data may have included names, email IDs, phone numbers, hashed passwords, and "encrypted or unencrypted security questions and answers."

This attack is separate from the one Yahoo disclosed back in September, in which the company believed a "state-sponsored actor" compromised its servers to access user data from over 500 million accounts. However, it looks like the same hackers were able to make away with more data this time around.

From the official announcement on Tumblr:

As we previously disclosed in November, law enforcement provided us with data files that a third party claimed was Yahoo user data. We analyzed this data with the assistance of outside forensic experts and found that it appears to be Yahoo user data. Based on further analysis of this data by the forensic experts, we believe an unauthorized third party, in August 2013, stole data associated with more than one billion user accounts. We have not been able to identify the intrusion associated with this theft. We believe this incident is likely distinct from the incident we disclosed on September 22, 2016.For potentially affected accounts, the stolen user account information may have included names, email addresses, telephone numbers, dates of birth, hashed passwords (using MD5) and, in some cases, encrypted or unencrypted security questions and answers. The investigation indicates that the stolen information did not include passwords in clear text, payment card data, or bank account information. Payment card data and bank account information are not stored in the system the company believes was affected.

Yahoo also said that the hackers were able to forge the company's authentication "cookies," allowing them access to user accounts without the need for a password:

Based on the ongoing investigation, we believe an unauthorized third party accessed our proprietary code to learn how to forge cookies. The outside forensic experts have identified user accounts for which they believe forged cookies were taken or used. We are notifying the affected account holders, and have invalidated the forged cookies. We have connected some of this activity to the same state-sponsored actor believed to be responsible for the data theft the company disclosed on September 22, 2016.

If you have a Yahoo account, it's time you changed your password. Create a strong password, and ensure the password you use on the service isn't reused anywhere else. You should also enable two-factor authentication for your Yahoo account.

Harish Jonnalagadda
Senior Editor - Asia

Harish Jonnalagadda is a Senior Editor overseeing Asia at Android Central. He leads the site's coverage of Chinese phone brands, contributing to reviews, features, and buying guides. He also writes about storage servers, audio products, and the semiconductor industry. Contact him on Twitter at @chunkynerd.

  • Damn , they got my fantasy football lineups
  • Same thing I was thinking. That's really the only reason I still have this email address.
  • I wouldn't even have/use my Yahoo account, but when I first started with my Android phone that is the account I used. I bought a ton of music, movies, and apps with that account that I still use. I wish there was a way to switch purchases over to my Gmail account so i could be done with Yahoo.
  • I pretty much did the same thing, but gradually now I'm moving all my stuff from Yahoo! to Gmail. It is taking time, but eventually, I... will.. succeed. :)
  • But for Google Play purchases I'm $hit out of luck. I'd really like to be done with Yahoo.
  • I received an email from Yahoo yesterday informing me that my account was identified as one of the over the 1 billion accounts hacked in 2013.
  • So did 1/7 of the world's population. I got one, too, and I went in to change my password, and there's no place on the User Account page to do that.
  • Same here.. Activate two step verification ASAP, and change pw.
  • It's time they start prosecuting the decision makers who willfully elect not to immediately disclose theft of information that they hold on individuals, it is also time to factor in scale of the incident when coupled with a willful, deliberate act. As in take the fear, anxiety and potential cost to an individual when identity theft occurs and as in this case multiply it by 1 billion. With the sheer scale metric considered these decision makers go away forever
  • Im pretty sure mine was hacked I can't even log on anymore.
  • I closed my account years ago. Something about their chat that pissed me off.
  • Just closed my account. So much for my fantasy football information.
  • Yahoo the movie. A story about a CEO who drove the company into the ground and cashed in when selling! Coming to theaters soon!
  • Sheesh sucks to to own a Yahoo account.
  • So, this happened in 2013. I have changed my password several times since then. I am assuming, therefor, that I do not need to do that now? (Yes, I know that it is a god idea to change passwords anyhow now and then, but I am just asking.)
  • I typically change my password every 3-6 months. This happened back in 2013 and they are just now saying something!
  • Good thing I only use Yahoo to read poorly written stories on mundane topics.
  • How do you STEAL what is PUBLIC....people wake up NOTHING is private in this PLANET omg anything you THINK is private is because it is ALLOWED or made BELIEVE to be that way....LMAO humans
  • I'll bet you're fun at parties
  • One thing I can say is Yahoo email on my BlackBerry was so fast and reliable. Gmail on my Nexuses/Pixel not so much.
  • Perhaps this is why when I get mail that says it came from a friend but obviously was hacked, it is usually a yahoo account., I used to get a lot of these but most people have gotten away from using yahoo as their primary email.