Opinion: This article is chock full o' SMM/UEFI/Firmware technical information. Definitely worth a read.

Also, another excerpt:

"I sent my reports to Intel Platform Security and Incident Response Team at 15.07.2016 and after several working days and short e-mail conversation both Intel and AMI confirmed all of the security issues. Intel decided to release a single advisory INTEL-SA-00057 to cover all four vulnerabilities. Fixed firmware for my NUC of version SYSKLi35.86A.0051 was released at 10.08.2016 — not bad, especially as for the job that requires coordinated work of two different companies."