Merge branch 'main' into dep-apst1-9183716

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Gary Moore 2024-08-05 14:06:31 -07:00 committed by GitHub
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@ -37,8 +37,6 @@ The most common sources of conflicting configurations include:
```cmd ```cmd
Location= HKLM:SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\DoNotConnectToWindowsUpdateInternetLocations Value=Any Location= HKLM:SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\DoNotConnectToWindowsUpdateInternetLocations Value=Any
Location= HKLM:SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\DisableWindowsUpdateAccess Value=Any Location= HKLM:SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\DisableWindowsUpdateAccess Value=Any
Location= HKLM:SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\WUServer String=Any
Location= HKLM:SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU\UseWUServer Value=Any
Location= HKLM:SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU\NoAutoUpdate Value=Any Location= HKLM:SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU\NoAutoUpdate Value=Any
``` ```
@ -90,8 +88,6 @@ Copy and paste the following PowerShell script into PowerShell or a PowerShell e
```powershell ```powershell
Remove-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -Name "DoNotConnectToWindowsUpdateInternetLocations" Remove-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -Name "DoNotConnectToWindowsUpdateInternetLocations"
Remove-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -Name "DisableWindowsUpdateAccess" Remove-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -Name "DisableWindowsUpdateAccess"
Remove-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -Name "WUServer"
Remove-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "UseWUServer"
Remove-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "NoAutoUpdate" Remove-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "NoAutoUpdate"
``` ```
@ -104,8 +100,6 @@ Copy and paste the following code into a text editor, and save it with a `.cmd`
echo Deleting registry keys... echo Deleting registry keys...
reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" /v "DoNotConnectToWindowsUpdateInternetLocations" /f reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" /v "DoNotConnectToWindowsUpdateInternetLocations" /f
reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" /v "DisableWindowsUpdateAccess" /f reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" /v "DisableWindowsUpdateAccess" /f
reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" /v "WUServer" /f
reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" /v "UseWUServer" /f
reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" /v "NoAutoUpdate" /f reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" /v "NoAutoUpdate" /f
echo Registry keys deleted. echo Registry keys deleted.
Pause Pause
@ -120,9 +114,7 @@ Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate] [HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate]
"DoNotConnectToWindowsUpdateInternetLocations"=- "DoNotConnectToWindowsUpdateInternetLocations"=-
"DisableWindowsUpdateAccess"=- "DisableWindowsUpdateAccess"=-
"WUServer"=-
[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU] [HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU]
"UseWUServer"=-
"NoAutoUpdate"=- "NoAutoUpdate"=-
``` ```

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@ -96,20 +96,6 @@ An attacker might modify the boot manager configuration database (BCD), which is
An attacker might also replace the entire operating system disk while preserving the platform hardware and firmware, and could then extract a protected BitLocker key blob from the metadata of the victim OS partition. The attacker could then attempt to unseal that BitLocker key blob by calling the TPM API from an operating system under their control. This can't succeed because when Windows seals the BitLocker key to the TPM, it does it with a PCR 11 value of 0. To successfully unseal the blob, PCR 11 in the TPM must have a value of 0. However, when the boot manager passes the control to any boot loader (legitimate or rogue), it always changes PCR 11 to a value of 1. Since the PCR 11 value is guaranteed to be different after exiting the boot manager, the attacker can't unlock the BitLocker key. An attacker might also replace the entire operating system disk while preserving the platform hardware and firmware, and could then extract a protected BitLocker key blob from the metadata of the victim OS partition. The attacker could then attempt to unseal that BitLocker key blob by calling the TPM API from an operating system under their control. This can't succeed because when Windows seals the BitLocker key to the TPM, it does it with a PCR 11 value of 0. To successfully unseal the blob, PCR 11 in the TPM must have a value of 0. However, when the boot manager passes the control to any boot loader (legitimate or rogue), it always changes PCR 11 to a value of 1. Since the PCR 11 value is guaranteed to be different after exiting the boot manager, the attacker can't unlock the BitLocker key.
To prevent boot manger roll-back attacks, Windows updates released on and after July 2024 changed the default PCR Validation Profile for **UEFI with Secure Boot** from `7, 11` to `4, 7, 11`.
The PCR values map to:
- `PCR 4: Boot Manager`
- `PCR 7: Secure Boot State`
- `PCR 11: BitLocker access control`
> [!TIP]
> To check what PCRs are in use, execute the following command:
> ```cmd
> manage-bde.exe -protectors -get c:
> ```
## Attacker countermeasures ## Attacker countermeasures
The following sections cover mitigations for different types of attackers. The following sections cover mitigations for different types of attackers.

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@ -26,6 +26,3 @@ When this policy is enabled and the hardware is capable of using Secure Boot for
|--|--| |--|--|
| **CSP** | Not available | | **CSP** | Not available |
| **GPO** | **Computer Configuration** > **Administrative Templates** > **Windows Components** > **BitLocker Drive Encryption** > **Operating System Drives** | | **GPO** | **Computer Configuration** > **Administrative Templates** > **Windows Components** > **BitLocker Drive Encryption** > **Operating System Drives** |
> [!NOTE]
> To prevent boot manger roll-back attacks, Windows updates released on and after July 2024 changed the default PCR Validation Profile for **UEFI with Secure Boot** from `7, 11` to `4, 7, 11`.

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@ -26,8 +26,6 @@ A platform validation profile consists of a set of PCR indices ranging from 0 to
> [!NOTE] > [!NOTE]
> When Secure Boot State (PCR7) support is available, the default platform validation profile secures the encryption key using Secure Boot State (PCR 7) and the BitLocker access control (PCR 11). > When Secure Boot State (PCR7) support is available, the default platform validation profile secures the encryption key using Secure Boot State (PCR 7) and the BitLocker access control (PCR 11).
>
> To prevent boot manger roll-back attacks, Windows updates released on and after July 2024 changed the default PCR Validation Profile for **UEFI with Secure Boot** from `7, 11` to `4, 7, 11`.
The following list identifies all of the available PCRs: The following list identifies all of the available PCRs: