Microsoft BitLocker – YellowKey zero-day exploit
66 points
2 hours ago
| 9 comments
| tomshardware.com
| HN
otterley
1 hour ago
[-]
reply
misone
19 minutes ago
[-]
reply
DANmode
7 minutes ago
[-]
> Mitigation: Use Bitlocker with a PIN.

> (Note: The YellowKey author disagrees that PIN is a protection

reply
AnonC
1 hour ago
[-]
The BitLocker exploit seems simple and very dangerous. Companies and individuals have been relying on BitLocker to protect information if the device is lost. Despite promises, Microsoft doesn’t seem to be serious about security.

What will it take for more companies to truly understand their risks with Windows and being locked into Microsoft’s platforms?

reply
ranger_danger
1 hour ago
[-]
How does a bug equate to "not serious about security"?
reply
navigate8310
1 hour ago
[-]
There's no way this is not a backdoor
reply
Our_Benefactors
1 hour ago
[-]
Read the article. It’s pretty clear that this is a backdoor, and calling it a bug would be so generous as to be misleading.
reply
HDBaseT
15 minutes ago
[-]
It seems undeniably a backdoor, why on earth would a very specific folder/file name and a specific boot combination just "magically" open up an encrypted drive.

It also doesn't help this comes from a person who likely was close to the development at Microsoft (one way or another) as their recent disclosures are quite alarming.

Of course, this could technically be the stars aligning type bug, but it seems like a purposefully planted backdoor to me.

reply
forestry
1 hour ago
[-]
*in your opinion.
reply
forestry
1 hour ago
[-]
The blog author calls it that but given there’s no root cause yet it’s foolish to jump to conclusions.
reply
Nition
37 minutes ago
[-]
This looking so much like an intentional backdoor just makes me wonder even more about TrueCrypt's sudden recommendation in 2014 that everyone switch to BitLocker. This particular backdoor didn't exist then (it's only Win11 apparently) but this sure makes it seem more plausible that another one might have.

Though if TrueCrypt was killed to try and get people to switch to encryption that could be backdoored, then why allow its successor VeraCrypt to exist? It's open source and independently audited, so it really shouldn't be backdoored.

reply
Cakez0r
14 minutes ago
[-]
reply
ungreased0675
2 hours ago
[-]
Remarkable. Does MS take a huge reputational hit for having a backdoor, or are they so essential to most places this won’t matter?
reply
peroids
1 hour ago
[-]
I’m assuming the EU speeds up the uncoupling cause of some of this.
reply
charcircuit
47 minutes ago
[-]
It's not an actual backdoor. An attacker found a way to exploit Windows after booting it up in this recovery mode. The security of files on the device depends on it being impossible for Windows to be pwned by an attacker on any surface exposed before the user is unlocked.

This is why operating systems like GrapheneOS disable the USB port on the initial boot to limit the attack surface that an attacker has.

reply
ranger_danger
1 hour ago
[-]
As far as I can tell, there's no concrete evidence that it is actually an intentional "backdoor."
reply
skeptic_ai
48 minutes ago
[-]
lol it’s an obvious backdoor. No way a security system would ever allow this blatant workaround to bypass all encryption. Backdoor is the only answer
reply
majorchord
35 minutes ago
[-]
> lol it's an obvious backdoor

in your opinion

reply
pajko
1 hour ago
[-]
reply
ChrisArchitect
17 minutes ago
[-]
reply
bombcar
1 hour ago
[-]
How is this even possible, backdoor or no? Isn't the whole point of this type of encryption that even a compromised machine can't decrypt without the passphrase? If this works it means that the key is stored unencrypted somewhere?
reply
majorchord
1 hour ago
[-]
Most setups only have the key stored in the TPM, so all you need to get it back is a signed/trusted bootloader.

Ideally you'd want that key to be further protected with a password or some other mechanism because it's not impossible to extract TPM keys.

reply
andrecarini
1 hour ago
[-]
Presumably the key is stored in the TPM
reply
ranger_danger
1 hour ago
[-]
For those who use password (not PIN) based pre-boot authentication with BitLocker... do we know if that setup is safe?

I can't imagine there would be a way to bypass that if a password is required, unless it was a situation where like, there was originally some secret secondary key made that needs no password... or the password was never tied to the key in the first place.

reply
andrecarini
1 hour ago
[-]
The exploit developer themselves say [1] TPM+PIN is vulnerable, though no public PoC.

[1]: https://deadeclipse666.blogspot.com/2026/05/were-doing-silen...

reply
forestry
1 hour ago
[-]
I’m skeptical of that claim. The key material presumably is inaccessible even to the OS without the passcode.
reply
ranger_danger
48 minutes ago
[-]
> presumably

That's the thing, we don't actually know how involved the PIN is in relation to the key... it might be completely separate (and hence bypassable).

Similarly I also wonder if password-based pre-boot auth is affected.

reply