Although the original dump was removed from Beta Archive, the dumped data has already been copied on other sites such as Mega.nz iStock

Microsoft may once again be in hot water. A massive trove of confidential data containing Microsoft's internal Windows OS (operating systems) builds and parts of its source code have reportedly been leaked. The dumped data is reportedly believed to have been stolen from Microsoft's in-house systems in March.

The Register reported that 32 TB of Microsoft's confidential data was leaked on Beta Archive. The dump includes several Windows 10 builds and Windows Server 2016, none of which have been officially released by Microsoft. Some of the builds also reportedly contain private debug symbols, which are generally not released publicly by the tech giant and are thought to contain much more information about a piece of code, detailing how it works.

The data dump reportedly contains Microsoft's source code package dubbed the "Shared Source Kit," which includes data on USB, storage, and Wi-Fi stacks, and the Plug-and-Play system. This data can potentially be used by malicious hackers to scan it for vulnerabilities, which could then be exploited to launch a large-scale cyberattack on Windows systems across the globe.

The dump also reportedly includes versions of the Windows 10 "Mobile Adaptation Kit", which is a confidential software toolset used to run Windows OS on phones.

"The 'Shared Source Kit' folder did exist on the FTP until [The Register's] 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," Beta Archive told The Register.

BleepingComputer reported that although the original dump was removed from Beta Archive, the dumped data has already been copied on other sites such as Mega.nz.

It still remains unclear as to who leaked the massive treasure trove of Microsoft's data. However, Beta Archive told ArsTechnica that the private beta builds leaked appear to have come from various sources. Beta Archive also indicated that the leaks are not likely to be related to the recent arrests made by the UK police. Two men were arrested for conspiracy to gain "unauthorised access" to Microsoft's computer networks.

However, according to authorities, the two men are involved with partners across the globe. The police also said the investigation is still "in the early stages".

Microsoft is yet to comment on the matter.