Clarification on the hardware

[ziggythehamster]

I’m trying to figure out the capabilities of this device, which I want to use for security research purposes. Can you clarify what the two pieces are able to do / what their purpose is? I think the SD card side is a regular SD card with the ability for an ESP to take over the bus and do whatever it wants, and the other side is only a programmer for the ESP, and is not needed for communication with the ESP after programming. But I’m not sure if I’m right or not - that’s what I need a device to do, but it’s not explicitly said that the SD card is usable standalone (via WiFi) after programming.

If I’m correct, then I’d also love to know if it’s possible for the ESP to “proxy” to the SD card or if it’s only able to switch who has control (device inserted into / ESP). If the ESP can proxy requests (e.g. because the connector pins and internal memory device pins require passing through the ESP), that allows for interesting things like returning different data when the host device requests the same data twice (this is known as a TOCTOU attack). If it can’t do this, is it at least able to eavesdrop on requests made by the host device? I understand that the firmware might not support this yet, but I wanted to see if the device hardware could do it. A block diagram of the circuit/devices would probably be helpful to answer these questions too.

Thanks for any information you can share :)

[Guspaz]

I'd also like to know if there is any way for the ESP32 to take over or at least inject commands to the SPI pins. This would be very useful, as I could use some otherwise unused SPI commands and use it for serial communication between the ESP32 and the host device over the standard pins (since few devices have the extra UHS-II pins connected).