Hacker trades 272 million passwords for social media likes

The passwords and usernames belonged to accounts from Russia's largest email provider, Mail.Ru, as well as a smaller number of accounts each from Gmail, Yahoo Mail and Microsoft Hotmail. Though it doesn't mean there was a breach of the email services themselves, the cache, first reported by Reuters, contains a huge amount of data.

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.