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 organisations.
We have no evidence of customer data being affected and our investigation is ongoing.
This type of cyberattack is no surprise to Microsoft and other companies that must grapple with determined and persistent adversaries.
More top news
Cross-channel services face the possibility of ongoing disruption because of migrant activity in and around Calais.
Big companies will have to show that their supply chains do not use child slave labour or exploit people, David Cameron has announced.
Disneyland Paris is reportedly facing a pricing probe amid claims it charges British tourists more than its French customers.