Yahoo announced through their blog on Thursday customer usernames and passwords were stolen and may be used to access accounts.
An exact number on the affected accounts was not given, but Yahoo is the second largest email provider after Google's Gmail with 273 million Yahoo mail accounts worldwide with 81 million in the U.S. alone, according to research firm comScore, the Associated Press reported.
On their blog post Yahoo said a security breach had been detected and stated "the information sought in the attack seems to be names and email addresses from the affected accounts' most recent sent emails."
"Our ongoing investigation shows that malicious computer software used the list of usernames and passwords to access Yahoo Mail accounts," Yahoo said in the blog post written by Jay Rossiter, senior vice president of Platforms and Personalization Products.
The hacked information could be used to make spam and scam messages seem more legit, according to the AP. The information could also be used to access user banking and shopping sites and information.
The danger is the use of the hacked information to reset passwords on banking and shopping sites, the AP reported. With the Yahoo mail address the hacker could ask for a password reset to be sent to email account allowing access to private financial information.
Yahoo also said in the statement the hacked information was taken from a third-party database, though they did not explain why there would be a need to store information in a third-party data-base, the AP reported.
This is the second issue Yahoo has faced with their email accounts in two months; in December 2013 the email accounts were out for a couple of days and Yahoo CEO Marissa Mayer apologized to customers, according to the AP.
Yahoo said they have acted quickly and reset passwords on affected accounts along with implenting "additional measures," the AP reported. Yahoo said they could not comment due to an ongoing federal investigation.
