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
It should be the case that even administrator access should not be abusable

If administrator access is equivalent to ownership, then I strongly disagree.

>>userbi+Dvb
As an administrator, you generally expect to be able to change your mind at some point.

Flashing data? Fine.

Permanent? Not so much.

>>shakna+XHb
This logic doesn't hold. If I choose to dban or degauss something, I don't expect I should be able to recover it later. Admins absolutely have the option to make irreversible changes, and do this quite often.

>>ang_ci+M5c
Just because some administrative decisions are permanent and destructive doesn't mean that every operation should be made permanent or destructive.

Should every software config require buying new hardware because the initial config gets permanently flashed with an e-fuse to only allow a single write? You could even make a security argument for such a setup, but good luck getting approval for your 15th motherboard this quarter because you typo'd the config.

Also, dban and degaussing is not entirely equivalent -- from a practical perspective the equivalent is hard drive shredding (because the hardware cannot be used again in the old/non-malware config -- dban and degaussing are more like factory default resets). Do some organisations need to do this? Sure. Should we design systems with the assumption that any mistake means that the hardware is destined for the shredder? I would hope not...