At one billion records, it's the biggest data breach ever.
Law enforcement provided Yahoo in November 2016 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. Yahoo has 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. We are notifying potentially affected users and have taken steps to secure their accounts, including requiring users to change their passwords. Yahoo has also invalidated unencrypted security questions and answers so that they cannot be used to access an account.
Separately, our outside forensic experts have been investigating the creation of forged cookies that could allow an intruder to access users’ accounts without a password. Based on the ongoing investigation, the outside forensic experts have identified user accounts for which they believe forged cookies were taken or used in 2015 or 2016. The company is notifying the affected account holders, and has 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 we disclosed on September 22, 2016.
Yep, last time it was 500 million account details breached. Now Yahoo says that in August 2013, in what appears to have been a separate security incident, the details of one billion accounts (that's an awful lot of zeroes) was accessed by hackers.
The stolen information included names, email addresses, telephone numbers, dates of birth, hashed passwords (using MD5) and, in some cases, encrypted or unencrypted security questions and answers. No payment data was accessed.
As the news broke around the world (late in the evening here in the UK), I started my first ever YouTube live stream to discuss what appeared to have happened and answer questions.
It's horrendous news for Yahoo, which is trying to sell itself to Verizon. But it's even worse for the innocent users and companiesd whose information has been exposed as a result of this hack.
Yahoo's security chief Bob Lord posted that hackers are thought to have created forged cookies that could permit access to users' accounts without any password whatsoever.
Let that sink in for a moment. Malicious hackers have been able to break into Yahoo accounts since 2013, without any password.
As I describe in the video, if you are at risk you should ensure that:
- change your Yahoo password (make it strong and hard to crack).
- you are not using the same exposed password anywhere else on the internet. You should *never* re-use passwords.
- change your security questions & answers (get into the habit of lying in your security answers, so rather than using something easy to determine like your real mother's maiden name you choose something random like "UkCWm6)7.u74cu93YpR;" instead).
- use a password manager to remember what your passwords are, as well as your security answers.
- Watch out for phishing emails that pretend to come from Yahoo.
- enable two-step verification or two-factor authentication on your accounts, where available.
Incidents like this don't do any good at all for Yahoo's tarnished brand. You may want to consider switching your email account to somewhere else if you've lost trust in the company.
I'm afraid I just wouldn't trust Yahoo anymore, and can't recommend them to my friends and family.
Check out the Yahoo FAQ for more details and advice.
Further reading: How to delete your Yahoo account.