Microsoft already verified that the source code of Windows 10 is from the Shared Source Initiative and was probably accessible only to OEMs (Original Equipment Manufacturers) and partners.
“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”
The source code was posted on enthusiast site Beta Archive, but was also posted on a free private FTP where various archived Windows builds are also exist.
The rule of the website is that only beta builds that have been previously replaced by newer releases are accepted. “sourced from various forum members, Windows Insider members, and Microsoft Connect members.” Mean that the core source code is not accepted on the site.
The source code leakage caused an embarrassment for Microsoft, but the source code itself has been already shared with partners, enterprises, governments, and other customers who choose to license it through the Shared Source initiative.
The Microsoft Mobile Adaption Kit of Windows 10 was also involved in the leak, besides some Windows 10 Creators Update builds, and some ARM-based versions of Windows 10.
The admin of betaarchive.com said:
“First of all let us clear up a few facts. The “Shared Source Kit” folder did exist on the FTP until this article came to light. We have removed it from our FTP and listings pending further review just in case we missed something in our initial release. We currently have no plans to restore it until a full review of its contents is carried out and it is deemed acceptable under our rules.
The folder itself was 1.2GB in size, contained 12 releases each being 100MB. This is far from the claimed “32TB” as stated in The Register’s article, and cannot possibly cover “core source code” as it would be simply too small, not to mention it is against our rules to store such data.”