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?

It's fairly common in business devices before 8th gen Intel.

A click out of one... two is binding...

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

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.

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?

Should be noted that if a password is asked to decrypt the drive it also doesn't work.

LUKS is still vulnerable to this attack if you enable autodecrypt using TPM. This attack is based on the vulnerability that the CPU and TPM communicates uses plain text. And it is a pretty common attack against TPM:

https://dolosgroup.io/blog/2021/7/9/from-stolen-laptop-to-inside-the-company-network

SPI is a communication protocol for embedded systems and is extremely common amongst virtually all hardware. Due to its simplicity, there is no encryption option for SPI. Any encryption must be handled by the devices themselves. At the time of this writing BitLocker does not utilize any encrypted communication features of the TPM 2.0 standard, which means any data coming out of the TPM is coming out in plaintext, including the decryption key for Windows

And apparently Linux is not doing too hot on this regard either:

https://www.secura.com/blog/tpm-sniffing-attacks-against-non-bitlocker-targets

As we can see, parameter encryption simply isn't used in practice, and except for safeboot none of the solutions enforce PIN/MFA by default.

However, this attack is not viable for device with firmware based solution, like fTPM, Microsoft Pluton, secure enclave etc. in these case TPM is part of the cpu, hence have no exposed pins to sniff their connection.

So if you don't want people with physical access to your computer (a thief or a evil maiden) to access everything on your disk, don't setup TPM auto decrypt.

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

Not unless you entered your recovery code to unlock it on the old computer with the external tpm.

"Sniff the cod" This is a typo right? I don't know any better, but I had a good laugh.

Nope. As soon as you move the disk to your second system/TPM, you lose any ability to decrypt it at all.

The Key is stored on the Internal TPM. Only it can unlock the SSD.