Found this on one machine. Key expires in 5 days. System runs Linux only and has never booted Windows, ever. Secure boot may be off.
SHA1 Fingerprint: 46:de:f6:3b:5c:e6:1c:f8:ba:0d:e2:e6:63:9c:10:19:d0:ed:14:f3
Certificate:
Data:
Version: 3 (0x2)
Serial Number:
61:08:d3:c4:00:00:00:00:00:04
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=US, ST=Washington, L=Redmond, O=Microsoft Corporation, CN=Microsoft Corporation Third Party Marketplace Root
Validity
Not Before: Jun 27 21:22:45 2011 GMT
Not After : Jun 27 21:32:45 2026 GMT
Subject: C=US, ST=Washington, L=Redmond, O=Microsoft Corporation, CN=Microsoft Corporation UEFI CA 2011
I had to vouch your comment, not sure what happened there. Something in your technical output must have triggered HN. One can use mokutil to see if Secure Boot is enabled after installing it. I assume the OEM installation or update of the BIOS must have included that cert but I am just guessing.