Yahoo announced this week that it will alert users it suspects are being targeted by state-sponsored attackers.

"
We'll provide these specific notifications so that our users can take appropriate measures to protect their accounts and devices in light of these sophisticated attacks," Bob Lord, Yahoo's chief information security officer, wrote in a blog post .
If you do get an alert, Yahoo offered several protection options: turn on two-step verification ; create a strong password; make sure account recovery information, like emails and phone numbers, are up to date; double check your mail forwarding and reply-to settings because hackers could have messed with them; and review your account for activity you don't recognize.