The Washington Post's servers were recently broken into by a group of unknown origin that gained access to the user names and passwords of its employees, the paper said on Wednesday.
The extent of the loss of company data was not immediately clear, though officials are planning to ask all employees to change their user names and passwords, the newspaper said in a report. The Post said the passwords were encrypted. However, hackers in some cases have been able to decode encrypted passwords.
The Post did not see any evidence that the hackers accessed information about its subscribers, such as credit cards or home addresses. Nor were there immediate signs that they accessed the Post's publishing system or email, nor sensitive personal information of its employees, such as Social Security numbers.
Post officials learned of the intrusion on Wednesday from Mandiant, a cybersecurity contractor that monitors the paper's networks. The breach was of relatively short duration, maybe a few days at most, and an investigation is ongoing, the story said, citing a Post spokeswoman. It marks at least the third intrusion for the paper over the past three years, according to the paper.
The Post could not be immediately reached for comment.
The Post suspects that Chinese hackers may be behind the intrusion. Evidence from a 2011 breach of the paper's network pointed to the involvement of Chinese hackers. Earlier this year, attacks on the The Wall Street Journal and The New York Times also raised suspicions of hacking from China.
The latest intrusion began with the breach of a server used by the Post's foreign staff which then spread to other company servers before being discovered, the paper said.