I have to centralize logs collection from many different widespread computers on which I can only plug USB flash drives. Those computers should not be reachable from the network in any case to prevent any network attack.
It must be hardware-level secured by design for the host computers against remote access (the logging system could crash but the host computers could not be compromised in any case) and I should be able to prove it. USB flash drives are the only authorized devices for security and certification reasons (even if a USB flash drive could still be infected :( ). So I don't have much choice.
I thought about designing a device acting as a USB flash drive on one side linked to an Ethernet interface on the other side. Any log written on the USB flash drive would be pushed to the Ethernet module, the Ethernet module would automatically send any incoming data to a target IP (centralized data logging system). The link between the USB and Ethernet module would be simplex (hardware design) so that no attack on the Ethernet module could compromise the USB flash drive connected on each computer.
I posted a similar question on https://electronics.stackexchange.com/questions/209885/secured-centralized-logs-collection-through-usb-flash-drives but we didn't come up with a solution maybe because I proposed an over engineered solution.
There might be a much simpler solution. I must find a cost effective solution with proven security guarantees (host computer unreachable even if USB module is compromised)
Thanks a lot for your help
PS: I cannot use the serial interface (which could have been a good solution)