Yahoo!

Still use Yahoo!? If you value your data at all, you'll stop using the online service right now. Enough is enough.

Not again. 1 billion user accounts have been compromised in yet another security breach at the company. This is on top of the hundreds of millions already affected by previous hacks. What makes this more terrifying is that the breach for this 1 billion account figure was actually back in August 2013.

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.

This is simply unacceptable. The official announcement states that those affected will be contacted and steps have already been taken to secure accounts. That said, the hack has already occurred, systems breached and data leaked. This data may have included names, email, phone numbers, birth dates, hashed passwords and even unencrypted security questions and answers. When you look at how the breach was possible, this story becomes even worse.

Separately, we previously disclosed that our outside forensic experts were investigating the creation of forged cookies that could allow an intruder to access users' accounts without 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 have to ask: do you really need your Yahoo! account? If not, we strongly recommend you delete it.