Info's of

Yahoo has said that usernames and passwords of its email

customers have been stolen and used to access accounts, but the

company isn't saying how many accounts have been affected.
A file photo of the Yahoo logo shown at the company's headquarters in Sunnyvale, California. Reuters Photo


Yahoo is the second-largest email service worldwide, after Google's

Gmail, according to the research firm comScore. There are 273

million Yahoo mail accounts worldwide, including 81 million in the

US.

Yahoo Inc. on Thursday said in a blog post on its breach that "The

information sought in the attack seems to be names and email

addresses from the affected accounts' most recent sent emails."

That could mean hackers were looking for additional email

addresses to send spam or scam messages. By grabbing real names

from those sent folders, hackers could try to make bogus messages

appear more legitimate to recipients.
Yahoo! CEO Marissa Mayer. Reuters Photo


The bigger danger: access to email accounts could lead to more

serious breaches involving banking and shopping sites.

That's because many sites use email to reset passwords.

Hackers could try logging in to such a site with the Yahoo email

address, for instance, and ask that a password reminder be sent by

email.

The breach is the second problem for Yahoo's mail service in two

months. In December, the service suffered a multi-day outage that

prompted Yahoo CEO Marissa Mayer issue an apology.

Yahoo said it believes the usernames and passwords weren't

collected from its own systems, but from a third-party database.

It's not clear why a third-party database would have information on

Yahoo accounts.

Yahoo said it is resetting passwords on affected accounts and has

"implemented additional measures" to block further attacks.

The company would not comment beyond the information in its

blog post. It said it is working with federal law enforcement.