It's probably more like a glorified "keylogger"
A simple KVM box with one of those low powered credit card PC's fitted inside, stick in a rechargeable battery and wire it to draw power from the usb input, It sits there day after day recording key strokes and mouse movements with the odd screen grab. the on board PC then compresses it in to manageable chunks of zips, rars or tar's and waits for one of the gang to walk into the Bank at a busy time of the day. Then it sends it to a receiver via wifi in the crooks bag/pocket in the 10-20 mins he is waiting to get served. If one visit is not enough then they hand it over to another member who gets in line and waits for it to finish.