[ikidd]

The bug this guy brings up is very obviously a Bitlocker backdoor and raises very serious questions about what Microsoft is doing with the encryption. Pretty certainly they're able to decode the volumes without the user's key, which is extremely concerning.

Looks like they're trying to make it disappear, but it's in the wild now.

[bri3d]

It’s a post-boot authentication bypass exploit. Any post-boot authentication bypass exploit against TPM-only sealed BitLocker effectively bypasses it. The user doesn’t have a key to start with in this setup, just the machine.

This exploit is cool but there are similar exploits discovered in any given year and nothing really reeks of a backdoor; this one seems to be gaining attention mostly because Microsoft’s robo-call level initial response caused the researcher to dramatically crash out.

[thewebguyd]

I wouldn't be surprised if this was intentionally put in, but I think its important to clarify that the encryption itself wasn't broken, and with this exploit specifically the drive also has to remain inside the original PC/TPM. It's a boot authentication bypass, not an encryption break.

As far as we know, having TPM+Pin or TPM+Startup Key breaks the exploit. TPM only was always known to be basically ineffective against threats like laptop theft, TPM only would only protect you if the drive was stolen out of the machine, which in that case, this exploit also would not work.

[cryo32]

I know someone who works for a nefarious gov org and they never put the bitlocker keys in the TPM on their laptops. You have to enter the password yourself on power up.

Wonder if they knew about this.

[tgsovlerkhgsel]

You don't need to be thinking of any specific vulnerability to realize that putting the decryption key next to the data you're trying to protect is a dumb idea.

If for example a laptop like that gets lost or stolen, the attacker has the data and the key, in a box they physically hold, with no attempt limit, and unless they actively mess with the boot process, it will happily load the key into memory for them. If it's a discrete TPM the attacker can likely sniff the key on the wire. If that doesn't work, they just need to find a vuln anywhere in the secure boot process, or in Windows, and again, they have the key. And if that doesn't work, they could sniff the memory bus, or do a cold boot attack (again, with unlimited attempts unless they irreparably damage the mainboard/TPM in the process).

[tatersolid]

The key is still in the TPM in that scenario it just requires a password to unlock it.

[LocalH]

It's a journal replay attack