Facebook hacked in latest cyberattack amid China suspicions

Facebook said hackers had infiltrated some of its employees' laptops in recent weeks, making the world's No 1 social network the latest victim of a wave of cyberattacks, many of which have been traced to China.

Facebook is working with the US Federal Bureau of Investigation to probe the malware attack.

The company said none of its users' data was compromised in the attack, which occurred after a handful of employees visited a website last month that infected their machines with so-called malware, according to a post on Facebook's official blog, released just before the three-day US President's Day weekend.

"As soon as we discovered the presence of the malware, we remediated all infected machines, informed law enforcement, and began a significant investigation that continues to this day," Facebook said.

It was not immediately clear why Facebook waited until now to announce the incident. The company declined to comment on the reason or the origin of the attack.

A security expert at a company with knowledge of the matter said he was told the Facebook attack appeared to have originated in China.

Twitter, the microblogging social network, said earlier this month it had been hacked and that about 250,000 user accounts were potentially compromised, with attackers gaining access to information including user names and email addresses.

Newspaper websites, including those of The New York Times, The Washington Post and The Wall Street Journal, have also been infiltrated. Those attacks were attributed by the news organisations to Chinese hackers targeting coverage of China.

Facebook noted in its blog post that it was not alone in the attack, and that "others were attacked and infiltrated recently as well", although it did not specify who.

Facebook described the attack as a "zero-day" infiltration, considered to be among the most sophisticated and dangerous types of computer hacks. Zero-day attacks, which are rarely discovered or disclosed by their targets, are costly to launch and suggest government involvement.

The incident could raise consumer concerns about privacy and the vulnerability of personal information stored in Facebook.

The types of information on the employee laptops that were compromised included "snippets" of Facebook source code and employee e-mails.

Facebook spotted a suspicious file and traced it back to an employee's laptop. After conducting a forensic examination of the laptop, it identified a malicious file, and then searched company-wide, identifying "several other compromised employee laptops".

In 2010, Google reported it had been penetrated via a "zero-day" flaw.

Additional reporting by Bloomberg