Microsoft has not indicated how many users have been affected by the breach, or who was involved in obtaining access to Outlook.com email accounts.
“Our data indicates that account-related information (but not the content of any e-mails) could have been viewed, but Microsoft has no indication why that information was viewed or how it may have been used,” says Microsoft in an email to affected users.
Microsoft had a similar attack back in 2017 when Windows development servers were breached for a number of weeks in January of the same year. The breach allowed hackers across Europe to access pre-release versions of Windows. The hackers weren’t able to steal login details or other personal information.
“Microsoft regrets any inconvenience caused by this issue,” says the security notification. “Please be assured that Microsoft takes data protection very seriously and has engaged its internal security and privacy teams in the investigation and resolution of the issue, as well as additional hardening of systems and processes to prevent such recurrence.”