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?
Note that RedSun and Bluehammer were silently patched, with no response to the CVEs by Microsoft, and not accrediting the researcher's work.
That's what this is about. Microsoft doing bad security practices while trying to get away with it, leading to this outcome.
The researcher also claims to have another version ready which allows to also bypass TPM+PIN via a similar backdoor, which I'm inclined to believe.
Why do I believe that? 5 ring 0 zero days within 3 months are so statistically unlikely to be found, by the same person, in such a short time. Whoever this person is really knows their exploits, and must be in the league of Juan Sacco.
the only way to bypass PIN would be an actual backdoor in Bitlocker. no way around that. an actual backdoor in microsoft encryption was never documented, and there are Snowden documents showing FBI pressing Microsoft into introducing one and Microsoft refusing
> the only way to bypass PIN would be an actual backdoor in Bitlocker. no way around that. an actual backdoor in microsoft encryption was never documented, and there are Snowden documents showing FBI pressing Microsoft into introducing one and Microsoft refusing
A USB stick containing a masterkey to decrypt a bitlocker volume is literally the definition of a backdoor.
Smells like a compromise. Microsoft enables BitLocker by default, thus protecting companies and users at scale. But the price is a backdoor they hope noone finds.
Someone else claimed this doesn't affect people who actually care about security and enable boot-time password protection.
> no, to access a bitlocker volume which automatically decrypts
> thats an LPE, not an encryption backdoor
No. RedSun and Bluehammer were LPEs
> the USB stick doesnt decrypt bitlocker, it just gives you root after bitlocker was AUTOMATICALLY decrypted
No, that's not what the bypass does. Maybe go try it out and verify it before you come to your quickly made conclusions?
It's not tied to "automatically decrypted" volumes, whatever that would imply for your setup requiring a pretty pointless TPM keystore for that.
If your case were true, it would also imply that any bitlocker cryptography never really worked because it was automatically decryptable without the need for a password/hash/whatever to get your keys from the keystore, which actually makes it so much worse. Even worse than the previously known coldboot attacks.
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.
Just booting opens up the encrypted drive. Windows gets the key out of the TPM.
Which leaves an enormous attack surface. If you can break Windows before logging in, you can effectively bypass bitlocker.
"Windows loads some file in System Volume Information automatically" is not evidence of a backdoor. And you have to put specific exploit files in there to turn this into an attack. You don't just make the folder.
It's still possible this is a backdoor, I guess, but there's nothing as blatant as you're implying.
That’s the most puzzling part to me. What’s the point of the PIN then? I was assuming it was mixed with the TPM secret somehow but if it can be bypassed then it shows it just an IF statement somewhere. Dang…
God I hate this stupid design of burying the decryption key in the TPM and hoping the software does not get fooled to reveal it.
Microsoft always sucks. Why don’t you ask for the password at boot time and derive the key from it. So much simpler and makes this kind of attacks impossible. Nobody is going to bypass LUKS or FileVault like this.
The amount of trust put into buggy TPM implementations chock full of vulnerabilities has always confused me.
Does anyone really trust these shitty Windows laptop/desktop manufacturers to get these things right? These guys couldn't even get basic hardware features like trackpad drivers right.
> We tested this ourselves, and sure enough, not only does it work, it bears all the hallmarks of a backdoor, down to the exploit's files disappearing from the USB stick after it's used once.
I think anybody who has been paying attention has assumed for at least 20 years that all of Microsoft’s shit is backdoored anyway. I mean, the original Snowden revelations made that abundantly clear if it wasn’t before then.
Businesses use Microsoft because they figure if it’s backdoored it doesn’t matter and won’t affect them (because they aren’t terrorists or child pornographers or whatever, and they’d comply with a subpoena regardless of if Bitlocker is backdoored or not) and individuals who care about security and privacy put their shit on a Veracrypt drive somewhere else.
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.
Having a specific file name trigger the decryption to happen automatically, while also removing said files after this is achieved, is an extremely unlikely bug. I think for most people evaluating this, the onus is now on anyone thinking this is not a backdoor to prove how a mistake in the code can trigger this very specific scenario.
This is like finding out that an OS accepts an SSH private key circulating online that the sysadmin for those OS boxes never authorized, and saying "wait, we don't know that this is a backdoor into that system, the attackers just found a bug".
>Having a specific file name trigger the decryption
That is not what happens. There is nothing wrong with decrypting the drive. If you just powered on the computer normally, it will "trigger the decryption." There just isn't way to read a file from the lock screen. This exploit is getting you to a state where the drive is unlocked but the user has access to a command prompt. A command prompt, unlike a basic login screen gives the user the ability to actually see the contents of arbitrary files.
>specific file name
It's a specific file name because Windows stores transaction logs under that name. If it was a random name it wouldn't be able to exercise this vulnerable code.
>also removing said files after this is achieved
It doesn't seem farfetched for a transaction log to be deleted after it is successfully replayed.
What would you require to feel confident it is a backdoor?
Nadella gives a press release, "Alright guys, you got us fair and square. Backdoor on Bootlocker. Various versions of it for years on behalf of the spooks."
You are unlikely to ever get a confirmation of wrong doing. That being said, for a first line security posture, there is no way external media should have anything to do with the encryption process. Even if the OS chose to read a USB drive, to also delete the magical files is ridiculously suspect.
It could always be plain old incompetence, but that is a damning level of technical ineptitude assigned to such critical infrastructure. This is not a project you assign to the intern, but paranoid security experts. Multiple levels of code review and red-teaming.
> there is no way external media should have anything to do with the encryption process.
Does this exploit have external media having anything to do with the encryption process...?
> Even if the OS chose to read a USB drive, to also delete the magical files is ridiculously suspect.
It's files in System Volume Information describing a transaction or something. It makes sense for it to resolve that transaction when mounting the external drive, and to then delete the files. And that's if it's even windows itself triggering the deletion.
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.
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?
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.
If someone drops 5 confirmed ring 0 exploits/bypasses within 3 months and claims that they got a 6th one... why on earth would you doubt that the 6th one suddenly is fake?
Do you know how hard discovering even one of those is? And how many months of work it takes?
Here's the primary source: https://deadeclipse666.blogspot.com/2026/05/two-more-public-...
Other links:
https://github.com/Nightmare-Eclipse/YellowKey
https://github.com/Nightmare-Eclipse/GreenPlasma
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?
Note that RedSun and Bluehammer were silently patched, with no response to the CVEs by Microsoft, and not accrediting the researcher's work.
That's what this is about. Microsoft doing bad security practices while trying to get away with it, leading to this outcome.
The researcher also claims to have another version ready which allows to also bypass TPM+PIN via a similar backdoor, which I'm inclined to believe.
Why do I believe that? 5 ring 0 zero days within 3 months are so statistically unlikely to be found, by the same person, in such a short time. Whoever this person is really knows their exploits, and must be in the league of Juan Sacco.
the only way to bypass PIN would be an actual backdoor in Bitlocker. no way around that. an actual backdoor in microsoft encryption was never documented, and there are Snowden documents showing FBI pressing Microsoft into introducing one and Microsoft refusing
so I call bullshit on the PIN bypass
> the only way to bypass PIN would be an actual backdoor in Bitlocker. no way around that. an actual backdoor in microsoft encryption was never documented, and there are Snowden documents showing FBI pressing Microsoft into introducing one and Microsoft refusing
A USB stick containing a masterkey to decrypt a bitlocker volume is literally the definition of a backdoor.
Go on, try it out. It works.
no, to access a bitlocker volume which automatically decrypts
thats an LPE, not an encryption backdoor
the USB stick doesnt decrypt bitlocker, it just gives you root after bitlocker was AUTOMATICALLY decrypted
Smells like a compromise. Microsoft enables BitLocker by default, thus protecting companies and users at scale. But the price is a backdoor they hope noone finds.
Someone else claimed this doesn't affect people who actually care about security and enable boot-time password protection.
> no, to access a bitlocker volume which automatically decrypts
> thats an LPE, not an encryption backdoor
No. RedSun and Bluehammer were LPEs
> the USB stick doesnt decrypt bitlocker, it just gives you root after bitlocker was AUTOMATICALLY decrypted
No, that's not what the bypass does. Maybe go try it out and verify it before you come to your quickly made conclusions?
It's not tied to "automatically decrypted" volumes, whatever that would imply for your setup requiring a pretty pointless TPM keystore for that.
If your case were true, it would also imply that any bitlocker cryptography never really worked because it was automatically decryptable without the need for a password/hash/whatever to get your keys from the keystore, which actually makes it so much worse. Even worse than the previously known coldboot attacks.
How does a bug equate to "not serious about security"?
There's no way this is not a backdoor
Why would a "bug" also erase the evidence from the USB stick after someone gains access?
The blog author calls it that but given there’s no root cause yet it’s foolish to jump to conclusions.
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.
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.
Just booting opens up the encrypted drive. Windows gets the key out of the TPM.
Which leaves an enormous attack surface. If you can break Windows before logging in, you can effectively bypass bitlocker.
"Windows loads some file in System Volume Information automatically" is not evidence of a backdoor. And you have to put specific exploit files in there to turn this into an attack. You don't just make the folder.
It's still possible this is a backdoor, I guess, but there's nothing as blatant as you're implying.
*in your opinion.
https://infosec.exchange/@wdormann/116565129854382214
> Mitigation: Use Bitlocker with a PIN.
> (Note: The YellowKey author disagrees that PIN is a protection
That’s the most puzzling part to me. What’s the point of the PIN then? I was assuming it was mixed with the TPM secret somehow but if it can be bypassed then it shows it just an IF statement somewhere. Dang…
God I hate this stupid design of burying the decryption key in the TPM and hoping the software does not get fooled to reveal it.
Microsoft always sucks. Why don’t you ask for the password at boot time and derive the key from it. So much simpler and makes this kind of attacks impossible. Nobody is going to bypass LUKS or FileVault like this.
The amount of trust put into buggy TPM implementations chock full of vulnerabilities has always confused me.
Does anyone really trust these shitty Windows laptop/desktop manufacturers to get these things right? These guys couldn't even get basic hardware features like trackpad drivers right.
Usually the TPM is part of the CPU itself nowadays, so you're mostly trusting Intel or AMD.
An upgrade from terrible to bad.
They got it right - just not for us.
You can have a boot-time password for bitlocker. But that mode doesn't seem to get much use.
how about we wait for proof for such grandiose claims
author could become famous by being the first to proove an actual backdoor in an OS disk encryption
> We tested this ourselves, and sure enough, not only does it work, it bears all the hallmarks of a backdoor, down to the exploit's files disappearing from the USB stick after it's used once.
That's enough proof.
Remarkable. Does MS take a huge reputational hit for having a backdoor, or are they so essential to most places this won’t matter?
I don’t think anyone is using Windows for privacy, so I’d say nobody will care.
I think anybody who has been paying attention has assumed for at least 20 years that all of Microsoft’s shit is backdoored anyway. I mean, the original Snowden revelations made that abundantly clear if it wasn’t before then.
Businesses use Microsoft because they figure if it’s backdoored it doesn’t matter and won’t affect them (because they aren’t terrorists or child pornographers or whatever, and they’d comply with a subpoena regardless of if Bitlocker is backdoored or not) and individuals who care about security and privacy put their shit on a Veracrypt drive somewhere else.
I’m assuming the EU speeds up the uncoupling cause of some of this.
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.
Having a specific file name trigger the decryption to happen automatically, while also removing said files after this is achieved, is an extremely unlikely bug. I think for most people evaluating this, the onus is now on anyone thinking this is not a backdoor to prove how a mistake in the code can trigger this very specific scenario.
This is like finding out that an OS accepts an SSH private key circulating online that the sysadmin for those OS boxes never authorized, and saying "wait, we don't know that this is a backdoor into that system, the attackers just found a bug".
>Having a specific file name trigger the decryption
That is not what happens. There is nothing wrong with decrypting the drive. If you just powered on the computer normally, it will "trigger the decryption." There just isn't way to read a file from the lock screen. This exploit is getting you to a state where the drive is unlocked but the user has access to a command prompt. A command prompt, unlike a basic login screen gives the user the ability to actually see the contents of arbitrary files.
>specific file name
It's a specific file name because Windows stores transaction logs under that name. If it was a random name it wouldn't be able to exercise this vulnerable code.
>also removing said files after this is achieved
It doesn't seem farfetched for a transaction log to be deleted after it is successfully replayed.
This is 1000% a backdoor if you understand how the BitLocker process works.
I would appreciate for you to share an explanation with everyone else here as I am not intimate with Windows internals.
As far as I can tell, there's no concrete evidence that it is actually an intentional "backdoor."
What would you require to feel confident it is a backdoor?
Nadella gives a press release, "Alright guys, you got us fair and square. Backdoor on Bootlocker. Various versions of it for years on behalf of the spooks."
You are unlikely to ever get a confirmation of wrong doing. That being said, for a first line security posture, there is no way external media should have anything to do with the encryption process. Even if the OS chose to read a USB drive, to also delete the magical files is ridiculously suspect.
It could always be plain old incompetence, but that is a damning level of technical ineptitude assigned to such critical infrastructure. This is not a project you assign to the intern, but paranoid security experts. Multiple levels of code review and red-teaming.
> there is no way external media should have anything to do with the encryption process.
Does this exploit have external media having anything to do with the encryption process...?
> Even if the OS chose to read a USB drive, to also delete the magical files is ridiculously suspect.
It's files in System Volume Information describing a transaction or something. It makes sense for it to resolve that transaction when mounting the external drive, and to then delete the files. And that's if it's even windows itself triggering the deletion.
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
> lol it's an obvious backdoor
in your opinion
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.
Funny you should say that... https://news.ycombinator.com/item?id=47690977
What's with all the replies on these threads downplaying this? Why is it mainly brand new accounts? What's going on here?
I've seen every variant of:
1) "this is an authentication/privilege escalation bug, not a bitlocker exploit" (? what are you even trying to say)
2) "even though the attacker explicitly warns that this is capable of bypassing TPM+PIN, that isn't actually true or what he meant"
3) "we shouldn't jump to conclusions that this is a backdoor"
4) "we already knew BitLocker with just TPM isn't secure" (? except many organizations depend on it to be)
Most submissions involving criticism of big tech gets those kind of replies. Par for the course here.
You just have to skip reading them because it seems there's no stopping those 100% genuine replies
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?
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.
Presumably the key is stored in the TPM
Earlier thread: https://news.ycombinator.com/item?id=48114997
[dupe] https://news.ycombinator.com/item?id=48129789
And earlier
https://news.ycombinator.com/item?id=48114997
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.
The exploit developer themselves say [1] TPM+PIN is vulnerable, though no public PoC.
[1]: https://deadeclipse666.blogspot.com/2026/05/were-doing-silen...
I’m skeptical of that claim. The key material presumably is inaccessible even to the OS without the passcode.
If someone drops 5 confirmed ring 0 exploits/bypasses within 3 months and claims that they got a 6th one... why on earth would you doubt that the 6th one suddenly is fake?
Do you know how hard discovering even one of those is? And how many months of work it takes?
this claim is in another galaxy, not your average 0-day
> 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.