Intel PCIe Switch firmware package and LED mode toggle tool before version MR4_1.0b1: Improper access control

Impact

Improper access control in the PCIe switch firmware package and its management tool lets a privileged local user escalate. The PCIe switch is the fabric between the CPU complex and the GPUs, NVMe and NICs inside a node - it decides which device can DMA where. Firmware-level control of the switch means an attacker can re-map or observe traffic between accelerators and the host, which is below every isolation boundary the OS or hypervisor enforces, and it persists in the switch's own flash across any host reimage and across tenant handoff. This is the kind of component operators rarely inventory at all, so exposure tends to be unmeasured rather than accepted.

Who can reach it

A privileged local user on the host running the vendor firmware/management tooling against the switch.

What to do

Update the PCIe switch firmware package to MR4_1.0b1 or later. In practice this is delivered by the system builder (Supermicro, Gigabyte, Quanta, Wiwynn and the GPU-system ODMs) rather than by Intel directly, and it is one of the least reliably shipped firmware components in the stack - you will often have to ask the integrator for it by name. Requires the node quiesced and power-cycled. Remove the LED mode toggle tool and other switch management binaries from tenant-visible host images.

References