Hackers target Microsoft India's online store website
Microsoft India's online store was forced to close after an apparent hacking attack from a group calling itself Evil Shadow Team.
For a while after the attack, reports said screen shots of customers' details were posted on the site before it was taken offline by the company.
Microsoft said it was "investigating a limited compromise".
Customer data was found unencrypted on the site, the purported hacker told Reuters news agency.
Microsoft would not confirm that data was not encrypted and in a statement said: "We are diligently working to remedy the issue and keep our customers protected."
A message on the site apologised to customers for the shutdown.
"The Microsoft Store India is currently unavailable. Microsoft is working to restore access as quickly as possible," the message said.
WPSauce first reported the breach according to a Times of India report.
When the online store was hacked, the site had the picture of the Guy Fawkes mask, an image usually associated with the hacker group Anonymous, reports say.
High profile victims of Anonymous have included websites associated with the CIA as well as UN websites.