Yahoo warns users of account breaches related to recent attacks

'A forged cookie may have been used ... to access your account'

Yahoo has begun warning individual users that their accounts with the service may have been compromised in a massive data breach it reported late last year.

The warning, in email messages sent from Yahoo CISO Bob Lord, tell users that a forged cookie may have been used to access their accounts in previous years.

The warning to Yahoo users come at the same time that news reports suggest that Verizon Communications, in negotiations to buy Yahoo, may be seeking a discount of US$250 million because of the data breaches.

In December, Yahoo reported that data associated with more than 1 billion user accounts was stolen in August 2013. Less than three months earlier, the company reported a separate data breach affecting more than 500 million users that originally occurred in late 2014.

In a new warning to users sent Wednesday, Yahoo said the forged cookie problem allowed hackers to gain access to user accounts without passwords. The company connected the issue to the breach it reported in September.

"Based on the ongoing investigation, we believe a forged cookie may have been used in 2015 or 2016 to access your account," the new email from Yahoo says. "We have connected some of the cookie forging activity to the same state-sponsored actor believed to be responsible for the data theft we disclosed on Sept. 22, 2016."

Yahoo has not identified the state-sponsored actor. The new email was sent to users whose accounts were breached in what was apparently a general attack. Individual users who seem to have been specifically targeted by the state-sponsored actor were sent an additional notice.

Yahoo recommended that users review their accounts for suspicious activity, be cautious of unsolicited communications that ask for personal information, and avoid clicking on links or downloading attachments from suspicious email messages. The company asked users to consider adopting its Yahoo Account Key, an authentication tool that eliminates the need for a password.

"We invalidated the forged cookies and hardened our systems to secure them against similar attacks," Yahoo said in the new email. "We continuously enhance our safeguards and systems that detect and prevent unauthorized access to user accounts."

Join the PC World newsletter!

Error: Please check your email address.

Tags cybersecurityYahoobreach

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Grant Gross

IDG News Service
Show Comments

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

Azadeh Williams

HP OfficeJet Pro 8730

A smarter way to print for busy small business owners, combining speedy printing with scanning and copying, making it easier to produce high quality documents and images at a touch of a button.

Andrew Grant

HP OfficeJet Pro 8730

I've had a multifunction printer in the office going on 10 years now. It was a neat bit of kit back in the day -- print, copy, scan, fax -- when printing over WiFi felt a bit like magic. It’s seen better days though and an upgrade’s well overdue. This HP OfficeJet Pro 8730 looks like it ticks all the same boxes: print, copy, scan, and fax. (Really? Does anyone fax anything any more? I guess it's good to know the facility’s there, just in case.) Printing over WiFi is more-or- less standard these days.

Ed Dawson

HP OfficeJet Pro 8730

As a freelance writer who is always on the go, I like my technology to be both efficient and effective so I can do my job well. The HP OfficeJet Pro 8730 Inkjet Printer ticks all the boxes in terms of form factor, performance and user interface.

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Aysha Strobbe

Windows 10 / HP Spectre x360

Ultimately, I think the Windows 10 environment is excellent for me as it caters for so many different uses. The inclusion of the Xbox app is also great for when you need some downtime too!

Mark Escubio

Windows 10 / Lenovo Yoga 910

For me, the Xbox Play Anywhere is a great new feature as it allows you to play your current Xbox games with higher resolutions and better graphics without forking out extra cash for another copy. Although available titles are still scarce, but I’m sure it will grow in time.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?