MSI installer strips inherited "ALL APPLICATION PACKAGES" ACE from install directory

[asklar]

MSI installer strips inherited "ALL APPLICATION PACKAGES" ACE from install directory

Description

The Windows MSI installer sets an explicit DACL on C:\Program Files\nodejs via the SetInstallDirPermission component in product.wxs, which replaces the inherited ACL from C:\Program Files. This removes the ALL APPLICATION PACKAGES (SID S-1-15-2-1) ACE that is normally inherited by all subdirectories under C:\Program Files.

Current behavior

The WiX <Permission> element maps to the MSI LockPermissions table, which replaces the entire DACL rather than merging with inherited ACEs. The current configuration only grants access to four principals:

<Component Id="SetInstallDirPermission" Guid="{EFFC4F74-183A-4237-BBD7-0CAD2B950053}">
  <CreateFolder>
    <Permission User="[WIX_ACCOUNT_USERS]" GenericRead="yes" Traverse="yes" GenericExecute="yes" Synchronize="yes"
                GenericWrite="no" WriteAttributes="no" WriteExtendedAttributes="no"/>
    <Permission User="[AUTHENTICATED_USERS]" GenericRead="yes" Traverse="yes" GenericExecute="yes" Synchronize="yes"
                GenericWrite="no" WriteAttributes="no" WriteExtendedAttributes="no"/>
    <Permission User="[WIX_ACCOUNT_ADMINISTRATORS]" GenericAll="yes"/>
    <Permission User="[WIX_ACCOUNT_LOCALSYSTEM]" GenericAll="yes"/>
  </CreateFolder>
</Component>

You can verify this by comparing the ACLs:

# Other Program Files subdirectories have ALL APPLICATION PACKAGES
icacls "C:\Program Files\dotnet"
# ... APPLICATION PACKAGES:(OI)(CI)(RX) ...

# Node.js does not
icacls "C:\Program Files\nodejs"
# Only shows Users, Authenticated Users, Administrators, SYSTEM

Expected behavior

The nodejs directory should have the same ALL APPLICATION PACKAGES read/execute ACE that other C:\Program Files subdirectories inherit, allowing AppContainer-sandboxed processes to access Node.js.

Impact

Processes running in an AppContainer sandbox (e.g., UWP apps, sandboxed browser processes, and other packaged applications) cannot read or execute files under C:\Program Files\nodejs. This can cause failures when sandboxed processes need to invoke node.exe or resolve Node.js modules.

Suggested fix

Replace the <Permission> elements (which use the LockPermissions table and replace the DACL) with <PermissionEx> using an SDDL string that includes the ALL APPLICATION PACKAGES SID, or add a <Permission> entry for ALL APPLICATION PACKAGES. For example, using SDDL:

<CreateFolder>
  <PermissionEx Sddl="D:PAI(A;OICI;GRGX;;;BU)(A;OICI;GRGX;;;AU)(A;OICI;GA;;;BA)(A;OICI;GA;;;SY)(A;OICI;GRGX;;;AC)" />
</CreateFolder>

Where AC is the well-known SDDL abbreviation for ALL APPLICATION PACKAGES (S-1-15-2-1).

Environment

• OS: Windows 10/11
• Installer: MSI (WiX 4)
• Introduced in: WiX 4 migration (PR msi: migrate to WiX4 #45943), though the same issue likely existed in WiX 3