AMD Secure Processor - cryptographic key usage control: MULTI-TENANT ISOLATION: Once an attacker has arbitrary code

Impact

MULTI-TENANT ISOLATION: Once an attacker has arbitrary code execution inside the ASP, weak key-usage controls let them extract the ASP's cryptographic keys rather than merely using them. Extracted platform keys are portable: they can be used off-box to forge attestation material or decrypt data long after you have re-imaged the node, so this turns a contained firmware compromise into a lasting one.

Who can reach it

Local, and requires having already achieved code execution in the ASP - it is a privilege-amplifier chained behind one of the other ASP bugs, not a standalone entry point.

What to do

Fixed in AMD reference firmware (AGESA / SEV firmware) and delivered to you only as an OEM SBIOS/BIOS package - Dell, HPE, Supermicro, Lenovo, Gigabyte and the ODMs each rebuild and requalify AMD's AGESA drop before it ships. **Expect months, not weeks**: AMD publishes the bulletin, the OEM ships BIOS somewhere between one and six months later, and for platforms past their support window it may never arrive at all. Applying it is a full node power cycle with the host drained - not a driver reload, not a live patch. Track it as a firmware campaign per server SKU, not per kernel version, and verify afterwards by reading back the SMU/PSP firmware version rather than trusting the BIOS revision string. Because this sits inside the SEV-SNP trust boundary, the update also moves the platform's reported TCB version: after patching you must refresh VCEK certificates from AMD's KDS and update whatever attestation policy your tenants (or your own confidential-VM control plane) pin against, or every guest launch will start failing validation. If you have reason to believe a node's ASP was compromised, patching does not undo key extraction - the platform keys must be considered burned and the node's attestation identity retired.

References