Twitter says 250,000 users may have been compromised by an attack. The attack was not the work of amateurs, and we do not believe it was an isolated incident. The attackers were extremely sophisticated and we believe other companies and organizations have also been similarly attacked. Twitter urges users to change their passwords and disable Java on their computers in their browsers. For more information about making your Twitter and other Internet accounts more secure, read our Help Center documentation or the FTCs guide on passwords.”]
Source: https://blog.twitter.com/official/en_us/a/2013/keeping-our-users-secure.html