Twitter has become the latest victim in a number of high-profile cyber-attacks against media companies, saying hackers may have gained access to information on 250,000 of its more than 200 million active users. The social media giant said in a blog posting that earlier this week it detected attempts to gain access to its user data. It shut down one attack moments after it was detected. But it discovered that the attackers may have stolen user names, email addresses and encrypted passwords belonging to 250,000 users. Twitter reset the pilfered passwords and sent emails advising affected users.