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Yahoo Email Account Passwords Stolen
From: Audrey McNeil <audrey () riskbasedsecurity com>
Date: Fri, 31 Jan 2014 13:18:52 -0700


Usernames and passwords of some of Yahoo's email customers have been stolen
and used to gather personal information about people those Yahoo mail users
have recently corresponded with, the company said Thursday.

Yahoo didn't say how many accounts have been affected. 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 U.S.

It's the latest in a string of security breaches that have allowed hackers
to nab personal information using software that analysts say is ever more
sophisticated. Up to 70 million customers of Target stores had their
personal information and credit and debit card numbers compromised late
last year, and Neiman Marcus was the victim of a similar breach in December.

"It's an old trend, but it's much more exaggerated now because the programs
the bad guys use are much more sophisticated now," says Avivah Litan, a
security analyst at the technology research firm Gartner. "We're clearly
under attack."

Yahoo Inc. 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

"It's much more likely that I'd click on something from you if we email all
the time," says Richard Mogull, analyst and CEO of Securois, a security
research and advisory firm.

The bigger danger: access to email accounts could lead to more serious
breaches involving banking and shopping sites. That's because many people
reuse passwords across many sites, and also 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

Litan said hackers appear to be "trying to collect as much information as
they can on people. Putting all this stuff together makes it easier to
steal somebody's identity."

Yahoo said the usernames and passwords weren't collected from its own
systems, but from a third-party database.

Because so many people use the same passwords across multiple sites, it's
possible hackers broke in to some service that lets people use email
addresses as their usernames. The hackers could have grabbed passwords
stored at that service, filtered out the accounts with Yahoo addresses and
used that information to log in to Yahoo's mail systems, said Johannes
Ullrich, dean of research at the SANS Institute, a group devoted to
security research and education.

The breach is the second mishap for Yahoo's mail service in two months. In
December, the service suffered a multi-day outage that prompted Yahoo CEO
Marissa Mayer to issue an apology.

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.
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