A story in New York Times had indicated that the federal department found out about those attacks because of the alert system.
The attacks are a matter of concern because access to social media accounts can be lucrative for determined attackers. One account could yield access to dozens of others and open up lines of communication between people in a particular field or network. Twitter is offering suggestions like using Tor to anyone who is worried that their personal information is out in the wild.
Tor is free software for enabling anonymous communication and directs internet traffic through a free, worldwide, volunteer network to conceal a user's location and usage from anyone conducting network surveillance or traffic analysis.