Microsoft (NASDAQ:MSFT) raised eyebrows this week as it digs into a possible slip in its own defense. Bloomberg reports the company is probing whether a leak from its early alert system for cybersecurity firms opened the door for Chinese hackers to breach its SharePoint service.

Microsoft Corp. issued a progress report on what it described as the largest cybersecurity engineering project in history.

One of the hacked organizations reportedly includes the U.S. agency responsible for maintaining the country's stockpile of nuclear weapons. China-backed hackers have been observed carrying out the hacks targeting SharePoint servers.