additional: https://nakedsecurity.sophos.com/2014/10/10/fbis-warrantless...
> If the server uses full-disk encryption, and if it's well locked down, it would be nontrivial to secretly access and copy the server's data.
OP's article mentions this, part of the reason they move out of the US is because RAM can be trivially read even if full disk encryption is used. Reading RAM still works in Iceland.
> RAM can be trivially read even if full disk encryption is used
I wouldn't say "trivially", but yes, it can be. But if you're that paranoid, you can embed key parts of the motherboard in alumina-filled epoxy. Its thermal conductivity is good, and you can add fins and fans as needed. You can even embed trip wires in the epoxy, to trigger system shutdown if tampered with.
A lot of this seems like security theater, especially while still hosted behind Cloudflare.
Yeah, here it does seem security theater.
But still, it was a good writeup. I mean, dropbear and all.
I have no clue why they're using VPS, after all that. I mean, if they're a real business, they ought to just setup a server, and ship it to Iceland. If the want the ease of VPS, it's easy to do secure KVM in a FDE server. Even with Docker containers within KVM, if you like.
But what I mainly meant is that a "real business" can afford to build secure servers, ship them to Iceland, and send trusted staff to set up and configure them.
You probably know this, but anyway. If you're setting up FDE with dropbear on a remote server, it's best to build the installer on the machine.
I dig around. So to remotely unlock LUKS, on bare-metal in datacenter, one can use custom initramfs, like https://github.com/mtth-bfft/dracut-dropbear-unlock
But still "boot time SSH server's key is stored unencrypted, man-in-the-middle attacks can also be carried out to recover the encryption key at boot time". Ideas?
> Full-disk encryption doesn't protect you against someone with physical access to the machine: the encryption key can be recovered from RAM at runtime (e.g. cold boot attacks), and since the boot time SSH server's key is stored unencrypted, man-in-the-middle attacks can also be carried out to recover the encryption key at boot time. Consider this in your threat model.
So yes, for "Evil mastermind, supervillains level" you gotta embed the RAM, and everything that would give adversaries physical access to the RAM, in alumina-filled epoxy. Or better, alumina-and-fiberglass-filled epoxy. The alumina gives you heat condictivity, and the fiberglass strength. Plus embedded trip wires to nuke the board if they're cut.
It's also prudent to disconnect all ports from the board, except for the NIC, and embed everything that could be used to reconnect them.
With that, it'd be very difficult to get anything from RAM. Attempts at physical access would destroy the system.
But I wonder if there's a way to reproducibly generate SSH key pairs from hardware IDs. That way, there'd be no keys stored in /boot, and they'd be generated at each boot. So only your hardware would have the right keys.
If this thing works, there is no need for remote ssh FDE unlocking.
And this could also work via dropbear. There'd still be an exposed dropbear SSH key in /boot. But it'd be the TPM that you're unlocking. And I assume that there are ways to verify the authenticity of the TPM via initramfs, before providing a password.
Am I understanding that right? It does seem more complicated. Especially given that you don't have physical access to the server.
Yup. Nope. The key is protected by TPM magic :). TPM measures stuff, then we put the key in TPM and seal it to PCRs 0-13 measurements (whole boot environment). At boot, TPM will allow tcsd daemon (part of initrd) to read LUKS key once, and only if all measurements match, this is as far as I got.
End result is unlocked volume, without any passphrase prompts, neither on console nor via ssh.
like some software that floods all the RAM and memory caches with erroneous data, and then the hardware solution of the epoxy trip wires.
For the trip wires thing, you can just have them apply 5VDC to the wrong RAM pins. And then, if you wanted to recover the motherboard, you'd need to chip out stuff, and replace it. But it's probably only the CPU that'd be worth recovering. And maybe you'd want to embed that too, just in case.