Over the New Year, Microsoft exposed nearly 250 million Customer Service and Support (CSS) records on the web. The records contained logs of conversations between Microsoft support agents and customers from all over the world, spanning a 14-year period from 2005 to December 2019. All of the data was left accessible to anyone with a web browser, with no password or other authentication needed.
The Comparitech security research team led by Bob Diachenko uncovered five Elasticsearch servers, each of which contained an apparently identical set of the 250 million records. Diachenko immediately notified Microsoft upon discovering the exposed data, and Microsoft took swift action to secure it.
Here is the full report – https://www.comparitech.com/blog/information-security/microsoft-customer-service-data-leak/