Password-less TPMs will always be fundamentally vulnerable. The only question is what is the price to break them. It can be very high (as seen in the Xbox).
faulTPM: Exposing AMD fTPMs' Deepest Secrets
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Re: faulTPM: Exposing AMD fTPMs' Deepest Secrets
#12>Our attacks have shown that an fTPM cannot sufficiently protect its internal state against firmware or physical attacks. In such a scenario, a passphrase-only key protector of reasonable length provides better security than a TPM-only protector with a numeric PIN (5.3.1). This is in stark contrast to Microsoft’s claim that “BitLocker provides the most protection when used with a Trusted Platform Module” [29] (see also in 2.3). In fact, of all available protectors (seen in Figure 1), TPM-only is arguably the weakest protection strategy.
This might not be surprising to some, despite Windows hiding the GUI passphrase functionality behind some group policy settings, both "Require additional authentication at startup" and "Enhanced PIN", which isn't perhaps the most intuitive and a normal user might not even realize unless they notice the "normal" PIN is numerical-only. In any case, for the average person that might have their devices stolen, this is likely not to be a threat, but I think a passphrase should always be preferable, BitLocker doesn't support any better option.
Re: faulTPM: Exposing AMD fTPMs' Deepest Secrets
#13Why not simply abandon TPM and focus on making simple, trustable, massively parallel general-purpose hardware without backdoors for spy agencies and corporations?
Whose computer is this, anyway?
Re: faulTPM: Exposing AMD fTPMs' Deepest Secrets
#14Honestly TPM is probably creating more bad than good at this point. Every time I think about the millions of computers that will be declared worthless this year, it makes me a little bit more angrier.
> Every time I think about the millions of computers that will be declared worthless this year, it makes me a little bit more angrier.
What is this a reference to? Every computer I've found will let you boot into the bios and disable secure boot or add new keys to the trust store.
Re: faulTPM: Exposing AMD fTPMs' Deepest Secrets
#15It says any TPM can be defeated in 2-3 hrs with physical access. Is the AMD one different? Can it be defeated over networks? And is this something I should be concerned about since I just bought a new AMD machine?
I am wondering the same, considering the proliferation of AMD in the last few years I would be devastated to have to go back to Intel. Just when the Framework came out with their AMD versions too.
Re: faulTPM: Exposing AMD fTPMs' Deepest Secrets
#16It says any TPM can be defeated in 2-3 hrs with physical access. Is the AMD one different? Can it be defeated over networks? And is this something I should be concerned about since I just bought a new AMD machine?
Yes, relevant in case of a lost device: "Motivated by Windows 11’s push to use the TPM for even more applications, we apply the vulnerability to Microsoft BitLocker and show the first fTPM-based attack against the popular Full Disk Encryption solution. BitLocker’s default TPM-only strategy manages – without any changes to the user experience – to swiftly step up a user’s security in the face of a lost or stolen devic…
Does this line imply then it is mostly a concern for Windows users? I don't mind only using Linux, it is Best in Slot for most tasks anyways.
Re: faulTPM: Exposing AMD fTPMs' Deepest Secrets
#17To anyone with a bit more breadth on this topic: is this as terrible as it sounds or more just in the realm of academia and nation-states?
Mostly academia and nation states. Physical access will always be king and this provides one more avenue for adversaries to bypass encryption more easily.
Re: faulTPM: Exposing AMD fTPMs' Deepest Secrets
#18It says any TPM can be defeated in 2-3 hrs with physical access. Is the AMD one different? Can it be defeated over networks? And is this something I should be concerned about since I just bought a new AMD machine?
One of the authors here. This attack is relevant if your machine is physically exposed to attacks, e.g., in an office environment or while traveling, and if you don't use any additional pre-boot passphrase to protect the disk (but rely solely on AMD's fTPM).
When TPMs became popular, dedicated TPMs were mainly used, being a separate chip on the mainboard connected via the SPI or LPC bus. These were prone to (relatively primitive) bus sniffing attacks, where you would hook up a Logic Analyzer to the bus, watch a regular boot procedure grab the disk key, and then use software like Dislocker to extract all data from a USB Live Linux or alike.
Nowadays, most modern CPUs (both on Intel and AMD) ship firmware TPMs that are "included" with CPU die, making them safe against the bus sniffing attacks. However, they can still be prone to more sophisticated attacks like ours.
Re: faulTPM: Exposing AMD fTPMs' Deepest Secrets
#19Honestly TPM is probably creating more bad than good at this point. Every time I think about the millions of computers that will be declared worthless this year, it makes me a little bit more angrier.
> Every time I think about the millions of computers that will be declared worthless this year, it makes me a little bit more angrier. What is this a reference to? Every computer I've found will let you boot into the bios and disable secure boot or add new keys to the trust store.
Microsoft is edging closer and closer to dropping support for Windows 10(even a computer I built in 2017 that's still running perfectly fine can't upgrade). But for many users, changing to another OS besides Windows is tantamount to not functioning, so planned obsolescence continues apace.
Re: faulTPM: Exposing AMD fTPMs' Deepest Secrets
#20Earlier quoted context omitted.
> Bitlocker's TPM- only protector - can be defeated by an attacker with 2-3 hours of physical access to the target device That sounds pretty practical.
Indeed it does, and this is just done by a team of researchers. Imagine what the NSA and their goons could get up to with 1000x more resources.
This is why you need to evaluate your threat model. Is the NSA out to get you? If so, I hope you aren't relying on HN for your security strategy. Are you worried about theft? Add a passphrase to your encrypted volume and don't rely on TPM. Worried about your coworker or family snooping on your computer and seeing your emails to your mistress? TPM is fine.