zlacker

>>zdw+(OP)
"If a potential attacker already has administrative access to the BMC..."

Then you've already lost.

The BMC needs to be ideally on a physically isolated network, or at least a separate one that has no route from the outside nor on the machine itself.

>>SoftTa+K5b
That’s a cop-out. It should be the case that even administrator access should not be abusable to implant permanent backdoors.

Anything that makes privileges escalation exploits more damaging is a real problem. I’m getting tired of how these are being dismissed as if admin access should mean that you can ignore any security issues. There are things that even admin accounts should not be able to change at the hardware level, or if they can they must be reversible in the future by another user with admin access.

> The BMC needs to be ideally on a physically isolated network, or at least a separate one that has no route from the outside nor on the machine itself.

This is good practice but it shouldn’t excuse poor security at the hardware level.

Supermicro motherboards also commonly default to having a feature that bonds the BMC network interface to one of the main NICs if you don’t plug a cable into the BMC interface. It’s common for people to be surprised that their BMC is exposed on their main network because they didn’t plug in a cable on the BMC NIC port at all.

>>Aurorn+S7b
I don't disagree, but if you have admin access to the BMC you can access the console, reboot the machine into single-user mode or even into another OS entirely, and then implant any malware you want, wipe the storage, etc.

Some of the Supermicro boards don't even have a separate BMC NIC, the only choice is to bond it to one of the main NICs or sacrifice one of them to be BMC only. I try to pay attention to that now after being surprised by that once on some servers we bought.

>>SoftTa+D8b
> but if you have admin access to the BMC you can access the console, reboot the machine into single-user mode or even into another OS entirely, and then implant any malware you want, wipe the storage, etc.

True in the common case, but this can/should be guarded against by disk encryption and secured boot chains.