CCC31 talk about UEFI security
Recently I presented at the 31st Chaos Communication Congress (together with Corey Kallenberg) and presented a talk titled “Attacks on UEFI security”. We described (and demoed) vulnerabilities allowing us to achieve write access to the flash chip (that stores UEFI code) and to SMM memory (that holds the code for the all-powerful System Management Mode). The CERT vulnerability notes are here, here and here ; you are also encouraged to read the presentation, the whitepaper and the second whitepaper.
TL;DR-style, these vulnerabilities are useful for an attacker who already has administrative privileges in the operating system, and wants to install a UEFI-based or SMM-based rootkit. So no, the sky is not falling, and this type of attack is not seen often in the wild. Yet some well knows cases are known, and as the topic gains quite some attention recently, there might be more in the future.