A massive trove of Microsoft’s internal Windows operating system builds and chunks of its core source code have leaked online.

The data – some 32TB of official and non-public installation images and software blueprints that compress down to 8TB – were uploaded to betaarchive.com, the latest load of files provided just earlier this week. It is believed the confidential data in this dump was exfiltrated from Microsoft’s in-house systems around March this year.

The leaked code is Microsoft’s Shared Source Kit: according to people who have seen its contents, it includes the source to the base Windows 10 hardware drivers plus Redmond’s PnP code, its USB and Wi-Fi stacks, its storage drivers, and ARM-specific OneCore kernel code.