A spokesperson said Thursday that the company immediately detected the breach and sent messages to users to change their passwords.
The policy shift at the world's largest software company follows similar moves since October by Facebook, Twitter and Yahoo.
Companies lost between $375 and $575 billion last year on hack attacks, according to cybersecurity firm Digital Guardian.
As criminals continue to evolve their tactics to steal personal and private information, it's becoming more difficult to identify holiday fraud.
Hackers may have been trying to obtain information such as email addresses, IP addresses, and/or phone numbers.
The cyber attack was the work of criminals, according to China's official Xinhua news agency.
A vigilante hacker's breach of 5 million accounts for the Hong Kong-based Internet-connected toy maker brings parents' worst nightmares into reality.
More than 1 billion usernames and passwords and 500 email addresses were allegedly stolen.
The hacker community that attacked PayPal and Mastercard is responding to the attacks in Paris.
In light of the recent hacks of high profile companies and individuals, entrepreneurs would do well to understand and maximize their online protection.
Victims' home addresses, birth dates and Social Security numbers could now be up for grabs on the black market.
Hackers who stole security clearance data on millions of Defense Department and other U.S. government employees got away with about 5.6 million fingerprint records, some 4.5 million more than initially reported, the government states.
Nearly 900,000 users' data was exposed.
Cyber-security companies are hiring by the droves, with some creating hundreds or thousands of jobs every year alone.
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© 2016 Entrepreneur Media, Inc.