Hackers broke into Yahoo!’s free email service, stealing the passwords and usernames of an undisclosed number of the firm’s 273 million accounts worldwide.
The company disclosed scant details of the coordinated hack attack, saying it had teamed up with federal law enforcement in the US, where 81 million accounts are registered, to investigate the security breach.
In a blog post on the company’s site, Yahoo! said “the information sought in the attack seems to be names and email addresses from the affected accounts’ most recent sent emails.”
Yahoo! said it recently discovered the breach, and suspects that malware was employed to take the user information from an undisclosed third party database.
“We have no evidence that they were obtained directly from Yahoo!’s systems,” wrote Jay Rossiter, the senior vice president in charge of Yahoo!’s platforms and personalization products.
Apart from seeking out and ultimately prosecuting those responsible for the attack, Rossiter said Yahoo! had “implemented additional measures to block attacks against Yahoo!’s systems.”
The company also reset the passwords of those affected, and sent out text messages to them so that they could “re-secure their accounts.”
Yahoo! is reportedly the second-largest worldwide email service, after Google’s Gmail, making it a likely target for hackers and online scammers.
In December, a hardware outage in one of Yahoo!’s storage systems left around 1 million users without access to their email accounts.
