Microsoft has apologised to consumers who say they have been infected by the anti-malicious software code called “mazda” and has removed the malware.
The statement came after the software maker said it had removed malware which could have been used to steal personal information.
The company said it would provide further details as soon as possible.
“This malware was used to infect multiple consumers’ computers,” said the company.
“We are working to find the criminals responsible for this.”
The statement by Microsoft comes as a court in the US ordered the software giant to turn over more details of the software, known as “Microsoft Defender”.
In a statement, Microsoft said it was cooperating with US prosecutors in the investigation.
“Microsoft has taken immediate steps to remove and investigate this malware.
Microsoft Defender has been used in at least nine countries to spy on US citizens,” the statement said.”
While this malware was not used to spy or steal any personal information, the malware did collect information about these individuals and other users in the context of their daily activities, such as accessing the internet, sending emails, sending text messages, browsing social networks, or using the internet to send and receive emails.”
Microsoft also said that it would make changes to its service to “reduce the risk” of such malware being used.
It said it did not have any plans to shut down the software.
In the UK, the Information Commissioner’s Office has asked Microsoft to turn down a request to stop sharing details about the software and has ordered it to release all customer data.
A spokeswoman for the Information Commissioners Office said it received information from a complaint in November that Microsoft had made “false or misleading representations” to consumers about how it uses its antivirus software.
“As soon as we received that information we contacted Microsoft and offered to assist in investigating the claim,” the spokeswoman said.
The watchdog said that the firm should provide a list of all customers affected by the software which it has said will be made public.
The government has said that Microsoft needs to disclose more information about how its anti-virus software works and is working with the industry body, the Computer Emergency Response Team, to get it to do so.