“Tech giants are increasingly doing more to notify users who are the victims of state-sponsored attacks. Google and Facebook will both notify you if they detect your account has been targeted or compromised, and now Yahoo is joining in as well. ‘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.”
Source: Yahoo joins Google and Facebook in warning users about state-sponsored attacks | The Verge