The company stopped one attack in its tracks, but after deeper investigation it was determined that attackers might have gained access to usernames, passwords and email addresses along with session data. From the looks of things, it affected about 250,000 users.
Affected users will receive (or may have received already) an email from Twitter explaining that passwords and session tokens have been revoked and will have to reset with a new password. Twitter also reminds users to exercise “good password hygiene” which is good advice for any user account. After all, you do not want to be one of the people that use weak passwords.
According to Twitter, “the attack was not the work of amateurs” and was “extremely sophisticated.” Twitter publicized the event in an effort to alert other companies whom may be suffering similar attacks. So, if you noticed that your links between Twitter and Facebook are not working, or you cannot Tweet pictures of your dinner from your phone, check your email and update the password to your account.