Some of these documents were marked confidential or restricted secret, and some are clearly just marketing material or manuals.
According to ZDNet's unnamed expert, the leak seems authentic and there are indeed confidential information among the leaked documents. This includes schematics for unreleased Tiger Lake platform, silicon and FSP source code packages, as well as encrypted Intel Boot Guard SDK.
There's no sensitive information about Intel's customers or employees, however.
Intel exconfidential Lake Platform Release ;)-- Tillie 1312 Kottmann #BLM 💛🤍💜🖤 (@deletescape) August 6, 2020
This is the first 20gb release in a series of large Intel leaks.
Most of the things here have NOT been published ANYWHERE before and are classified as confidential, under NDA or Intel Restricted Secret. pic.twitter.com/KE708HCIqu
Intel denies that they were really hacked. According to them, the information came from a customer portal Intel Resource and Design Center which hosts documents that Intel's partners are free to access.
Hacker claims that the documents came from an unsecure Akamai CDN server, and that furthermore the security was poor with the encrypted zip files. He said that password protecting the files was either Intel123 or intel123.
Kottmann said that this is only the first of many leaks to come from the hacker, so it'll remain to be seen whether the upcoming leaks worry Intel more than this one.