SuperMicro hardware has very extensive IPMI integration into the mothebroard, which amongst other things can take over and inject frames into the network interface, emulate a VGA device, talk to the CPUs serial lines directly, flash firmware, control the state of a number of physical devices- and this is what it supports just from the web interface it presents by default with the password "ADMIN:ADMIN". My money, based on experience attempting to harden their devices, is that any modification were injected into the IPMI hardware where most of this was already supported.

This stuff ends up being extremely difficult to disable. The naive approach would be to not connect to the dedicated NIC that's indicated on the back and in the instruction manual, but if you do this it masquerades onto the main NIC invisibly to the OS and DHCPs on its own to open up an administration port, web interface, and some assorted call homes. You have to explicitly tell it to use the non-connected port, change credentials, and modify it so that it is not accessible within operating system as well. Hopefully while the machine is offline to prevented any automated scanning finding it within your network.

The number of times I'd end up nmaping our local networks and being able to remotely access production hardware with an interface that allowed me to reach this interface was maddening. The system is basically designed to be as insecure as possible by default, and allow for the maximum possible persistent threats with BIOS flashing, IPMI flashing, and other completely nu-authenticated avenues exposed. The course of action was always just to write off the hardware and bin it, because god knows what impact you could actually have using that interface.