If by some trick outside software can invoke BIOS calls, it can read the data straight off the hardware. The MAC address can exist as a value burned in on each MAC's firmware or ROM; the value exists at a memory address one could query, or might be accessible through a chip in the HW implementing the Ethernet Phy layer, I believe. I'd have to go read old developer datasheets I haven't reference for 15 years to remember what the method is.
If by some trick outside software can invoke BIOS calls, it can read the data straight off the hardware. The MAC address can exist as a value burned in on each MAC's firmware or ROM; the value exists at a memory address one could query, or might be accessible through a chip in the HW implementing the Ethernet Phy layer, I believe. I'd have to go read old developer datasheets I haven't reference for 15 years to remember what the method is.