Microsoft hit by similar hack to Apple, Facebook
Hacking spree against tech firm continues after a few of Microsoft's Macs caught out
Microsoft admitted a small number of its computers, including some in its Mac software business unit, were infected with malware.
It said there no evidence of customer data being affected and it is continuing its investigation.
Microsoft said the security intrusion was "similar" to recent ones reported by Apple and Facebook.
The incident, reported on one of the company's public blogs happened "recently", but Microsoft said it chose not to make any statement publicly while it gathered information about the attack.
"During our investigation, we found a small number of computers, including some in our Mac business unit, that were infected by malicious software using techniques similar to those documented by other organizations," said Matt Thomlinson, general manager of Trustworthy Computing Security at Microsoft, in the company's blog post. "We have no evidence of customer data being affected and our investigation is ongoing."
"This type of cyber-attack is no surprise to Microsoft and other companies that must grapple with determined and persistent adversaries," he added.
Over the past week or so, both Apple and Facebook said computers used by employees were attacked after visiting a software developer website infected with malicious software.