Intel Boot Guard in Intel CSME / TXE / SPS: Insecure default initialisation in Boot Guard means the S3 resume path does

Impact

Insecure default initialisation in Boot Guard means the S3 resume path does not re-verify the boot chain, so an attacker who can modify firmware while the machine is suspended defeats verified boot. Boot Guard is the hardware root of trust the rest of your platform attestation chains to - if it does not hold on resume, it does not hold.

Who can reach it

An attacker able to modify platform firmware, typically with physical access or an existing firmware-write primitive, against a machine that suspends.

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. Servers that never suspend are largely out of scope, which is most of a datacenter fleet - but verify rather than assume, because management controllers do use low-power states.

References

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