Intel CSME firmware (TOCTOU): A time-of-check/time-of-use race in CSME firmware lets a privileged local user escalate

Impact

A time-of-check/time-of-use race in CSME firmware lets a privileged local user escalate into the management engine. Recent, and a reminder that the CSME attack surface is still producing findings on current platforms.

Who can reach it

Privileged local access on the host, plus winning a race.

What to do

Fixed in Intel CSME/SPS firmware, which reaches you as an OEM BIOS or firmware package - not as a microcode or OS update. That means: wait for your server vendor to ship it, drain the node, flash, and reboot. OEM availability is the long pole and routinely lags the Intel advisory by one or more quarters on server platforms. Track it per platform SKU, because vendors ship these unevenly across their own product lines.

References