Intel SGX / DDR4 memory bus (physical interposer): MULTI-TENANT ISOLATION: WireTap: a low-cost passive DDR4 interposer

Impact

MULTI-TENANT ISOLATION: WireTap: a low-cost passive DDR4 interposer reads the memory bus of an SGX machine and recovers the platform's attestation key, letting the attacker forge quotes that Intel's own attestation service accepts. The consequence for an operator is that SGX remote attestation no longer proves anything about a machine an adversary has had physical access to - which includes colocation, transit, and any hardware that has left your custody. Notably the published work reports the attack against production DCAP attestation, not a lab-only configuration.

Who can reach it

Physical access to the machine long enough to install an interposer between the CPU and a DIMM. Not remote, but well within reach of anyone in the supply chain, a colo neighbour with cage access, or an insider in a datacenter you do not own.

What to do

Unpatchable in the field on affected parts - deterministic memory encryption without integrity or freshness is a design property of SGX on these generations, not a bug with a patch. Operator response is procedural: treat physical custody as part of the SGX trust boundary, refuse to accept attestation from hardware outside your custody chain, and plan migration to platforms with stronger memory integrity. Watch for Intel TCB recovery advisories, but do not assume one will close this.

References