Hacker trades 272 million passwords for social media likes - CNET

Mail.Ru said the company was examining the data to see how many passwords were currently connected to email accounts. "As we have enough information we will wa the users who might have been affected," the company said in the statement. "Mail.Ru email service has been working hard to continuously improve its security system."

Yahoo said it is also trying to examine the list of credentials.

"We've seen the reports and our team is reaching out to Hold Security to obtain the list of accounts now. We'll update going forward," the company said in a statement.

Microsoft representatives didn't immediately respond to a request for comment. The company confirmed to Reuters that password-and-useame caches are a real problem but didn't specifically comment on whether this cache contained its users' login information.

Google declined to comment on the specific incident. The company wrote a blog post in 2014 about the problem of "password dumps," offering tips to users on what to do when such lists are posted online.

"It's important to note that in this case and in others, the leaked useames and passwords were not the result of a breach of Google systems," the company wrote in the blog post, which responded to a different data dump.

Even though the hacker practically gave the login information away for free in the data dump revealed Wednesday, it's valuable to email users, who would do well to change their passwords often and never reuse them on other accounts, Holden said. They should also take advantage of two-factor authentication on their most valuable accounts, he said, even if it's a little inconvenient.

That's the login technique that verifies who you are by sending you a text message or push notification to a separate phone or tablet. Mail.Ru said in a statement that it began offering a two-factor system last year, along with other increased safety measures; the other affected email providers also offer that service.