Wash. Post, Twitter reveal that hackers targeted them

Twitter said in a blog post on Friday it detected attempts to gain access to its user data earlier in the week. It shut down one attack moments after it was detected.

But Twitter discovered that the attackers may have stolen user names, email addresses and encrypted passwords belonging to 250,000 users they describe as "a very small percentage of our users." The company reset the pilfered passwords and sent emails advising the affected users.

The Twitter attack comes on after recent hacks into computer systems of U.S. companies, including The New York Times and The Wall Street Journal.

On Friday, The Washington Post disclosed in an article published on its website that it was also the target of a sophisticated cyberattack, which was discovered in 2011 and was first reported by an independent cybersecurity blog. Washington Post spokeswoman, Kris Coratti, didn't offer any details including the duration of the attack or the origins.

According to her comments made to the newspaper, the company worked with security company Mandiant to "detect, investigate and remediate the situation promptly at the end of 2011."

China has been accused of mounting a widespread, aggressive cyber-spying campaign for several years, trying to steal classified information and corporate secrets and to intimidate critics. The Chinese foreign ministry could not be reached for comment Saturday, but the Chinese government has said those accusations are baseless and that China itself is a victim of cyberattacks.

Twitter didn't provide any clues as to whether it believes that China was behind its hack. However, the blog post by the company's director of information security, Bob Lord, made clear that the hackers knew what they were doing. "The attackers were extremely sophisticated, and we believe other companies and organizations have also been recently similarly attacked," Lord said.