The cache of secret information is 20GB large and comes from an unknown source. It was announced as the first part in a series of Intel leaks. The developer was told that the information was stolen from Intel in a breach this year. Intel said that the data appears to be from the Intel Resource and Design Center, which hosts information for our customers and partners, which use information by our customers, use by our partners, and use it to provide information to our partners. The hacker claims they were able to test for default username access and unsecured access to files.
Source: https://www.bleepingcomputer.com/news/security/intel-leak-20gb-of-source-code-internal-docs-from-alleged-breach/