Yahoo's email users are only the latest in a growing list of those affected by hacks and other security breaches.

The company has announced via Tumblr post that a coordinated effort gained access to Yahoo Mail accounts.

There's no word on how many accounts were breached, but Yahoo revealed it believes the list of usernames and passwords used to carry out the attack likely came from a compromised third-party database.

The investigation is ongoing, and it appears malicious software was the conduit through which the hackers accessed the accounts. The attackers appeared to target names and email address from recently sent messages.

User protection

In light of the breach, impacted users were prompted to change their passwords. They'll have to go through a two-step sign-in process to access their account.

Federal law enforcement is on the case, Yahoo said.

The attack comes less than a week after Gmail suffered a brief outage, one that Yahoo quickly pounced on with its Twitter account. Maybe next time a rival service goes down, Yahoo will think twice about taunting?