For those who ever owned a Yahoo account, there is big chance that their data maintained by the online giant might have been already compromised. A massive Yahoo hack affecting 1 billion users has been revealed, eclipsing the previously known hacking incident which involved 500 million users.

The massive Yahoo hack actually happened back in 2013, according to a The New York Times report. What is worrying is that the attack gave hackers access to sensitive information such as encrypted password, names, phone numbers, birth dates. Even the security questions needed to effect password resets has been compromised, making it possible for the hackers to change passwords of the affected email addresses at will.

With the threat of online security threats such as identity theft at the back of everyone's mind, Yahoo drew flack for the company's perceived slow response to the data breach. While Yahoo recently forced users that were affected to change their passwords as well as nullified previously assigned security questions, critics say that the company did not act fast enough, considering that a discovery of a separate hacking incident has been made as early as September.

While no bank account information or credit card data are reported to be included in the hack, experts suggest that users should take steps in negating whatever security threats the Yahoo hack might have exposed them to. Email exchanges usually contain harmless information but it is also likely that it may be used to relay sensitive information that may be used in future attacks.

To counter these potential online security threats, CNBC suggests that users need to regularly change their passwords. It is also recommended for users to use a different password for different email accounts as an added step in case one of the email addresses has been compromised.

In addition, online users affected by the massive Yahoo hack are encouraged to review the email documents currently in their mail boxes. Those containing sensitive information, the type they do not want to fall into the wrong hands, must be deleted.

A two-step authentication process for all login attempts is also preferable. There are services that texts a code to a preselected cell phone number, ensuring that both the cell phone and the password are correct, providing an added layer of security.

If one is unsure of an incoming email, it is safer to leave it unopened, in case it may contain malwares. But if one has already opened a mail and has some suspicions about it, the attachments must never be opened.

The discovery of the massive 1 billion Yahoo hack came after a very recent discovery of a separate breach which happened back in 2014. On September 2016, Yahoo previously announced of a security breach affecting 500 million user email accounts.