Bitcoin account compromised. Bank refuse to refund.

unforeseen wrote: »

Ethernet packets contain the MAC address of the originating device

Ethernet packets only get you as far as your gateway router. The originating MAC address is not preserved in the IP packets that get the traffic from there, across the internet, to the bank's website. The MAC address will be changed many times along the way at each router carrying the traffic.

londoninvestor wrote: »

Indeed. And while a phone app or "fat client" PC app could be designed to include the source MAC address in the message payload (as opposed to packet headers), a browser-based tool can't, because the browser doesn't have access to the MAC address.

And MAC addresses can easily be spoofed anyway. If the network card supports promiscuous mode, the OS can use any MAC address it likes, and ignore the network card's burned-in address.