Permission of Authenticated users on C set to deny to all

[andrew_ng]

I got windows 11 working fine.
Tried install windows 10 on an other disk and then tried to make windows 10 unable to access to windows 11's disk by messing around with permission.
Set Authenticated Users deny to all on the windows 11' disk.

From then windows 11 can't run anymore as it cannot access to disk to boot.

Anyone have any ideas to reset that permission ?

 

[Callistemon]

The permissions for Windows 11's disk is entirely within Windows 10, and has no effect on boot. It's probably something during the installation process of Windows 10 that caused Windows 11 to become unbootable. Does a blue error screen appear when starting Windows 11? If so, what's it say, Boot Configuration Data, winload.efi, or something else?

 

[ubuysa]

The permissions for Windows 11's disk is entirely within Windows 10, and has no effect on boot. It's probably something during the installation process of Windows 10 that caused Windows 11 to become unbootable. Does a blue error screen appear when starting Windows 11? If so, what's it say, Boot Configuration Data, winload.efi, or something else?

I don't believe that's true (about the file permissions being in Windows 10). The Discretionary Access Control Lists (DACLs) that define who has what access to files and folders are stored in the NTFS file system itself, and alongside the files. Changing these DACLs in Windows 10 will also impact Windows 11 using the same files.

 

[Callistemon]

I was being stupidly wrong again, as always. Only the Administrators and Users groups are defined by computer name, not Authenticated Users or System. I thought this because an elevated Command Prompt is denied from deleting anything in the WindowsApps folder, so is a scheduled task running under System set with highest privileges, but items in WindowsApps folder can be deleted from Recovery Environment that boots separately. Apparently this does not apply to everything. I was stupid in assuming this would always be the same, which is quite a stupid and extreme assumption.

 

[andrew_ng]

The permissions for Windows 11's disk is entirely within Windows 10, and has no effect on boot. It's probably something during the installation process of Windows 10 that caused Windows 11 to become unbootable. Does a blue error screen appear when starting Windows 11? If so, what's it say, Boot Configuration Data, winload.efi, or something else?

Hi it was my mistake
Windows boot was fine. Only after login, it shown black empty desktop and error that could not connect to network as could not access the windows folder as I remember.

 

[andrew_ng]

I don't believe that's true (about the file permissions being in Windows 10). The Discretionary Access Control Lists (DACLs) that define who has what access to files and folders are stored in the NTFS file system itself, and alongside the files. Changing these DACLs in Windows 10 will also impact Windows 11 using the same files.

That's true.

The permissions settings tab shows groups like
Administrator (DESKTOP-EQOWO/Administrator)
Users (DESKTOP-EQOWO/Administrator)

the part DESKTOP-EQOWO/Administrator made me think that the permissions will affect only groups of that running OS. Groups of other OS like DESKTOP-12345 run on other disk are not affected - BUT THAT'S WRONG. The permission will affect on both DESKTOP-EQOWO and DESKTOP-12345.

I think the only way to limit the access it must point out the account which needs to be limited.

 

[ubuysa]

That's true.

The permissions settings tab shows groups like
Administrator (DESKTOP-EQOWO/Administrator)
Users (DESKTOP-EQOWO/Administrator)

the part DESKTOP-EQOWO/Administrator made me think that the permissions will affect only groups of that running OS. Groups of other OS like DESKTOP-12345 run on other disk are not affected - BUT THAT'S WRONG. The permission will affect on both DESKTOP-EQOWO and DESKTOP-12345.

I think the only way to limit the access it must point out the account which needs to be limited.

Can you not just go into Disk Management in WIndows 10 and remove the drive letter for your WIndows 11 system drive? That will stop any Windows 10 apps from accessing the Windows 11 drive.

 

[Callistemon]

Hi it was my mistake
Windows boot was fine. Only after login, it shown black empty desktop and error that could not connect to network as could not access the windows folder as I remember.

It's probably that the permissions set from the Windows 10 side affect groups with less privileges, so the Windows 11 system is able to start since most system files run with high privileges, until it reaches Windows Explorer, which doesn't load since that runs standard.

 

[Callistemon]

Can you not just go into Disk Management in WIndows 10 and remove the drive letter for your WIndows 11 system drive? That will stop any Windows 10 apps from accessing the Windows 11 drive.

This is the good solution, not the stupid rubbish that I say. It can be done from Disk Management, but if it doesn't persist across restart, the solution is to create a task with Task Scheduler that runs a CMD file. The letter of the other Windows could vary, so it's best to reference the dismounting command by volume GUID.

To find the GUID, open Command Prompt as administrator and use mountvol X:\ /L replacing X with the letter of the other Windows shown in File Explorer. Copy the long string surrounded with braces.

Then use SCHTASKS /CREATE /SC ONSTART /TN "Dismounting Windows 10" /TR "C:\Windows\System32\mountvol.exe \\?\volume\{GUID}\ /d" /RU SYSTEM replacing {GUID} with the string from mountvol X:\ /L leaving braces in.

 

[ubuysa]

This is the good solution, not the stupid rubbish that I say. It can be done from Disk Management, but if it doesn't persist across restart, the solution is to create a task with Task Scheduler that runs a CMD file. The letter of the other Windows could vary, so it's best to reference the dismounting command by volume GUID.

To find the GUID, open Command Prompt as administrator and use mountvol X:\ /L replacing X with the letter of the other Windows shown in File Explorer. Copy the long string surrounded with braces.

Then use SCHTASKS /CREATE /SC ONSTART /TN "Dismounting Windows 10" /TR "C:\Windows\System32\mountvol.exe \\?\volume\{GUID}\ /d" /RU SYSTEM replacing {GUID} with the string from mountvol X:\ /L leaving braces in.

That's interesting. When I installed and dual booted Windows 11 alongside WIndows 10, the WIndows 11 system partition did not have a drive letter assigned in WIndows 10. Because I wanted to access the two Windows system drives from each other I added a drive letter for the other WIndows partition in each system - and they were preserved across reboots. I wonder whether that's because my two WIndows systems were in separate partitions on the same physical drive?