When using an external TPM. Which next to no one does.
Watch the video. It just means external to the CPU, not an external device.
They demo the attack on a Lenovo laptop in the first minute of the video.
Edit: nm I just realized that was a 10 year old laptop and they’re in all the modern procs. I’m a lot less impressed now.
Sounds like intel has external and amd internal with their ftpm?
Many systems still use discrete tpms. Just because the CPU has a virtual tpm function doesn’t mean it’s used
fTPM has a bug, don’t know if it’s fixed
https://www.techspot.com/news/93684-amd-promises-fix-ftpm-issue-causes-stuttering-freezes.html
Veracrypt also doesn’t recommend using encryption that relies on TPMs
Some encryption programs use TPM to prevent attacks. Will VeraCrypt use it too? No. Those programs use TPM to protect against attacks that require the attacker to have administrator privileges, or physical access to the computer, and the attacker needs you to use the computer after such an access. However, if any of these conditions is met, it is actually impossible to secure the computer (see below) and, therefore, you must stop using it (instead of relying on TPM).
If the attacker has administrator privileges, he can, for example, reset the TPM, capture the content of RAM (containing master keys) or content of files stored on mounted VeraCrypt volumes (decrypted on the fly), which can then be sent to the attacker over the Internet or saved to an unencrypted local drive (from which the attacker might be able to read it later, when he gains physical access to the computer).
https://veracrypt.eu/en/FAQ.html
Let’s assume the attackers were law enforcers
It’s fairly common in business devices before 8th gen Intel.
Hi this is BitLockPickingLawyer here and today we’ll see how secure . . .
A click out of one… two is binding…
Say it with me now: LUUUUUKS
I wondered why LUUUUUKS didnt use the TPM, why do i have to put my password in… this is absolutely why.
Edit: fixed spelling of LUUUUUKS
Also yes you can, I wouldn’t recommend it though. Maybe in addition to your password though.
Wait until you see Dracut and Tang.
Very end of the article explains you need access to the TPM communication hardware, which no longer occurs external to Intel and And cpus
To *newer Intel and AMD cpus and only certain models.
There’s a lot of current hardware that uses embedded TPMs. It also depends on the communication path between the CPU and the module, but chances are it will be clear text and in some, via LPC.
Should be noted that if a password is asked to decrypt the drive it also doesn’t work.
So offline (external) bitlocker drives that are unlocked with the key only.
Or internal bitlocker drives that are unlocked with AMD fTPM are excluded from this exploit?
I thought the point of the TPM was that the keys would be kept internally to the TPM at all times and that any data lanes would only be used for transferring payload. Why are they sending keys between the TPM and the CPU?
There are some functions like that, like Passkey signing. For Bitlocker, the encryption/decryption key is transferred to the CPU (and RAM) in order for it to operate. The problem described here has been around for a while, but putting it on a key like that makes the attack method available to “everyone”. There has been a solution for a while too: 1) put in pre-boot Bitlocker PIN, and 2) use integrated TPM like the article mentions.
Because the CPU has to decrypt the bulk of the data coming from the disc. And it needs a key to do that. Unless we route all traffic through the TPM to decrypt the disc. The CPU needs a key to do that
Surely some smart key exchange algorithm could be used for that, e.g. the CPU provides a public key to the TPM and the TPM encrypts the symmetric disk key with that public key. Similar to how TLS works.
The private key would have to stored in clear text somewhere. Potentially if you had non volatile space on cpu that to store the private key, that might work. But if you’re going to do that, might as well just use an ftpm.
Why not store it directly in the TPM, if that’s the device that will do that initial decryption?
Question: if I have an bitlocker encrypted SSD in a modern computer with embedded TPM, can I move this SSD to an old computer with external TPM to sniff the cod this way? Be gentle. I am dumb. Thanks.
Not unless you entered your recovery code to unlock it on the old computer with the external tpm.
Nope. As soon as you move the disk to your second system/TPM, you lose any ability to decrypt it at all.
It seems to me an evolution on this attack: https://arstechnica.com/gadgets/2021/08/how-to-go-from-stolen-pc-to-network-intrusion-in-30-minutes/
Solution: Just encrypt it with a password.
Bit locker is a password controlled drive encryption. Am I being dumb or are you seriously saying that?
I guess they mean use the password as part of the encryption key, or encrypt the key with the password. Bitlocker doesn’t use the user’s password in that way, which is why it can boot an encrypted system without user interaction. That part always seemed very sketchy to me.
FYI: You can set it to require a PIN + TPM, or even just a password eg using
manage-bde -on c: -password.https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/manage-bde-on
Thanks, that sounds really useful. I’m guessing it won’t work unless you’re local admin though.
Yep, you’ll need local admin of course.
Which kind of makes it useless in many corporate environments where it’s most needed, since the users won’t be able to set their own password.
I mean, if it’s a corporate device then it’s really a policy IT should be setting - this can be easily be done via a GPO or Intune policy, where an elevated script can prompt the end-user for a password.
Yes.
Finally, we can install Linux on your corporate pc or grab some RAM from it 😂😂😂
That sounds about right for a Microsoft product’s security
You’re being downvoted because this is a hardware problem and not Microsoft’s fault.
Just look at the Xbox one mod chip scene and you’ll see MS can do security perfectly well.
Don’t know anything about that scene, has it ever been cracked?
Nope. Never. It’s pretty impressive.
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You are not really wrong, TPM was designed by Trusted Computing Group consisting of big tech companies like M$, IBM, AMD, Intel, Cisco and HP.
