On the other hand, given that the code was already meant to be available to "qualified customers, enterprises, governments, and partners" its release may not be such a big deal after all, as Microsoft may already have an expectation that this data could one day leak. "Our review confirms that these files are actually a portion of the source code from the Shared Source Initiative and is used by OEMs and partners", a Microsoft spokesperson told site in an email.
The leaked data had around 32TB of official and non-public Windows installation images and software, which were compressed down to 8TB.
Microsoft Windows beta testers and members with access to the Beta Archive can still get this confidential data for free.
The source code leaked online has two important modules including USB and Wi-Fi for Windows 10. The confidential Windows team-only internal builds were created by Microsoft engineers for bug-hunting and testing purposes, and include private debugging symbols that are usually stripped out for public releases.
Furthermore, the leak also includes several builds of Microsoft's Windows 10 Mobile Adaptation Kit which is a top-secret tool to enable the OS to run on multiple portable or mobile devices.
"We have removed it from our FTP and listings pending further review just in case that we missed something in our initial release. We now have no plans to restore it until a full review of its contents is carried out and it is deemed acceptable under our rules". In a statement, they also claimed that the builds came from different sources, not a single leak. "This is far from the claimed "32TB" as stated in The Register's article, and can not possibly cover "core source code" as it would be simply too small, not to mention it is against our rules to store such data", they further added.
Microsoft did not immediately respond to a request for comment.