TLDR if you actually want to act upon that : Takeaways The use of a discrete (physical) TPM actually decreases the security of the system, using a fTPM would solve the problem. If the discrete TPM has to be used, then a PIN or passphrase on BitLocker is necessary.
> The use of a discrete (physical) TPM actually decreases the security of the system, using a fTPM would solve the problem. Since only dTPM can be FIPS certified, I don't see how an uncertifiable piece of hardware can be more secure.
Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
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Re: Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
#12Since the key traverses the shared bus, does that mean that every component in the system could intercept the key just as easily as this logic analyzer does? Sounds like a supply chain security nightmare.
The point of this kind of encryption is that a removed hardrive can be sold or repurposed without data risk. Anyone can boot the laptop and get to the decrypted hard drive, what does it matter if they sniff the key first? They always had access to the end result of they can boot the laptop.
Re: Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
#13Earlier quoted context omitted.
> If the discrete TPM has to be used, then a PIN or passphrase on BitLocker is necessary. I always considered that BitLocker without a PIN is 80% convenience and 20% security.
IIRC earlier versions of bitlocker would rely upon SSD firmware implementations for drive encryption. They stopped doing that when it was revealed many of these hardware encryption systems in common drives didn't actually work.
void encryptSector(struct context *c, long sector_no, unsigned char *data, size_t data_len) {
// TODO
}Re: Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
#14>The use of a discrete (physical) TPM actually decreases the security of the system, using a fTPM would solve the problem. Errr... no. Using no TPM of any kind decreases your security. The discrete TPM's threat model was never designed to cover you from attackers using oscilloscope to probe your laptop's SPI bus during the boot process for unencrypted data. Unencrypted communications over any channel, SW or HW are ba…
Re: Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
#15>The use of a discrete (physical) TPM actually decreases the security of the system, using a fTPM would solve the problem. Errr... no. Using no TPM of any kind decreases your security. The discrete TPM's threat model was never designed to cover you from attackers using oscilloscope to probe your laptop's SPI bus during the boot process for unencrypted data. Unencrypted communications over any channel, SW or HW are ba…
fTPM is more secure against _this_ kind of attack, with physical access to the bus wires. However, since fTPM is a Firmware-TPM, it is vulnerable to all kinds of attacks on the system's firmware, even remotely, even via the network, even maybe if the computer is switched off. Remember all those (even unauthenticated, remote) XML-parser exploits in the Intel ME? fTPM is just one more ME module, and of course vulnerable to those exploits.
So overall, I consider fTPM a huge step back, because you might even get access without physical presence. For an fTPM, attack surface is far larger (because all of the ME software), minimum attack complexity may be smaller (because there will one day be a metasploit module for all those software problems, whereas HW hacking is always a certain hurdle), required attacker privileges are less (prolonged unobserved physical presence vs. network). Thus objectively worse in all aspects.
What would be better would be a dTPM that is integrated e.g. into a SoC, such that there are no exposed wires anywhere without decapping the SoC. Some systems such as phones work like that, but this is hard to tell even from the technical specs.
Re: Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
#16TLDR if you actually want to act upon that : Takeaways The use of a discrete (physical) TPM actually decreases the security of the system, using a fTPM would solve the problem. If the discrete TPM has to be used, then a PIN or passphrase on BitLocker is necessary.
> The use of a discrete (physical) TPM actually decreases the security of the system, using a fTPM would solve the problem. Since only dTPM can be FIPS certified, I don't see how an uncertifiable piece of hardware can be more secure.
It's incredibly slow to adapt to new technology.
fTPM has a different attack surface, and protects against this specific attack. It's most likely better than dTPM for hardware based attacks, but there's known attacks as well
Re: Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
#17Earlier quoted context omitted.
IIRC earlier versions of bitlocker would rely upon SSD firmware implementations for drive encryption. They stopped doing that when it was revealed many of these hardware encryption systems in common drives didn't actually work.
void encryptSector(struct context *c, long sector_no, unsigned char *data, size_t data_len) { // TODO }
Re: Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
#18>The use of a discrete (physical) TPM actually decreases the security of the system, using a fTPM would solve the problem. Errr... no. Using no TPM of any kind decreases your security. The discrete TPM's threat model was never designed to cover you from attackers using oscilloscope to probe your laptop's SPI bus during the boot process for unencrypted data. Unencrypted communications over any channel, SW or HW are ba…
Re: Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
#19Bitlocker is the Windows one, that's essentially known to be compromised, right? Not saying that it's useless, might be fine for certain work environments, but I wouldn't rely on it for anything truly personal.
It's not compromised if you set a PIN/passkey, aka use it correctly.
Technically, the lock on your house door is also compromised since any pro locksmith can open it within a few minutes, but that doesn't mean it's now useless to keep locking your door since most casual thieves aren't pro locksmiths and laptop thieves aren't gonna be black-hat hackers/security researchers.
Such security solutions are there to discourage low hanging fruits of amateur bad actors(99,99% of them) and make them give up and use their time somewhere else.
Re: Bypassing Bitlocker using a cheap logic analyzer on a Lenovo laptop
#20>The use of a discrete (physical) TPM actually decreases the security of the system, using a fTPM would solve the problem. Errr... no. Using no TPM of any kind decreases your security. The discrete TPM's threat model was never designed to cover you from attackers using oscilloscope to probe your laptop's SPI bus during the boot process for unencrypted data. Unencrypted communications over any channel, SW or HW are ba…
TPMs are slow and have rather restricted memory. They are fine for PCRs and some asymmetric operations.
But here they only unseal a key that is then used in software for speed. It's worse than something protected by a high entropy password. Which is still better than 90% of users would be otherwise