Friday 23 September 2016

Yahoo, The Biggest Cyber Data Theft in far

Yahoo have just disclosed over 500 million of its user accounts have been compromised, that's a huge number, think about it for second, that's half a billion people across the globe affected and at risk. This is largest known data breach in history to date. We know the Yahoo account data were stolen in late 2014, said the hack is said to have been orchestrated by state-sponsored actors, although there's no evidence to back this claim up.

Yahoo has not disclosed how the data was hacked, or why it has taken almost two years to either discover the breach or disclosure the breach publically. A cynic might say Yahoo delayed informing its massive user base until after it's recent £3.7 billion sale to Verizon was done and dusted. However in late July 2016 hackers were found offering 200 million Yahoo accounts for sale on the dark web (, so it is likely the 2014 data theft was discovered on the back of investigating that.

The stolen Yahoo account data included names, email addresses, telephone numbers, dates of birth, and security questions and answers. Surprisingly a chunk of the security questions and answers were not encrypted by Yahoo. I always recommend companies treat the protection of account security questions and answers at the same degree as account passwords, given they can be typically used just like a password access an account via a password reset function, including accounts used with other websites. This is especially important on email accounts, as often that is where the password reset links are sent as part of the password reset process.

Advice 1: Reset Your Yahoo Password
Yahoo stated account passwords were stored as a hashed value using bcrypt. That's good practice, especially in using bcrypt. However my advice is to play it safe and reset the password, it's good practice to change your password regularly anyway. And if you use that same password on any other websites, change it there too. 

Advice 2: Change Your Security Questions and Answers
Yahoo users should change their security question and answers, click here to do this on the Yahoo website. If users use the same Yahoo security questions and answers on other accounts, they also need to be changed, especially where they can be used to reset passwords and/or gain access to the account. Sure this will be a difficult task to check and complete, but Yahoo users should assume their Yahoo 'security questions and answers' together with their name, email address and date of birth, are known by cyber criminals.

Advice 3: Be Extra Vigilant
Yahoo users should be extra vigilant for phishing scam emails, which may be crafted using the stolen Yahoo personal information to look highly authentic. Also check for any suspicious activity in the email account, especially any signs that someone else has been using it.

1 comment:

Graham Oakman said...

That's fun how all these programmers try to compete each other.
And one wish to hide and protect data and another ones wish to steal that data and hide themselves.