Yahoo admitted recently that it had been hacked in a security breach that is being called one of the largest data breaches ever. The technology company said that in 2014 at least 500 million user accounts had been compromised, according to CNN. The company said it believes the hack was at the behest of a sovereign nation.

Yahoo said in a statement, according to CNN, that some of the information that was taken includes “names, email addresses, telephone numbers, dates of birth, hashed passwords (the vast majority with bcrypt) and, in some cases, encrypted or unencrypted security questions and answers.”

Yahoo is urging affected users to monitor their accounts for suspicious activity and is asking users to change their passwords. The company is also working with the FBI to find out who breached its security and how.

"The FBI is aware of the intrusion and investigating the matter," an FBI spokesperson said, according to CNN. "We take these types of breaches very seriously and will determine how this occurred and who is responsible. We will continue to work with the private sector and share information so they can safeguard their systems against the actions of persistent cyber criminals."

The day after Yahoo announced that the hack was genuine, Yahoo was sued in California for gross negligence, according to Channel NewsAsia.

Ronald Schwartz of New York filed the lawsuit on behalf of Yahoo users in the United States whose personal information was stolen in the 2014 hack. Schwartz alleges in his lawsuit that Yahoo was negligent because it didn’t take its users' privacy seriously, according to Channel NewsAsia. Schwartz is seeking damages and class action status.