Take ownership of a registry key, and change permissions

Question

Hello,
I am writing a powershell script to configure a W2008-R2 Server. In one of the steps, I need to take ownership of an existing registry key, and then give full control permissions to the administrators.
I have done this:
$acl = Get-Acl $key
$me = [System.Security.Principal.NTAccount]"$env:userdomain\$env:username"
$acl.SetOwner($me)
$person = [System.Security.Principal.NTAccount]"Administrators"
$access = [System.Security.AccessControl.RegistryRights]"FullControl"
$inheritance = [System.Security.AccessControl.InheritanceFlags]"None"
$propagation = [System.Security.AccessControl.PropagationFlags]"None"
$type = [System.Security.AccessControl.AccessControlType]"Allow"
$rule = New-Object System.Security.AccessControl.RegistryAccessRule($person,$access,$inheritance,$propagation,$type)
$acl.AddAccessRule($rule)
Set-Acl $key $acl
But it fails in "set-acl" command, with the message "Set-Acl : Requested registry access is not allowed."
Any ideas of how to do this? or if it is even possible?
Thank you!

Answer 1

Here is the code to take ownership of a registry key.  You first need to set the SeTakeOwnership permission on your process
The enable-privilege function is taken from a posting by Lee Holmes (http://www.leeholmes.com/blog/2010/09/24/adjusting-token-privileges-in-powershell/), but
I've been meaning to get around to tidy it up a bit for my purposes.  Perhaps this thread is the motivation I need to do this.  I should also note that the PowerShell Community Extensions has cmdlets to work with tokens already.  
I also never tested whether you can do the PowerShell native methods of get-acl set-acl if you set the token.  I don't have time to play with that now, but if you want to try it and let us know if it works that would be great.  The opensubkey method
I'm using I've documented here for changing permissions when you don't have permissions: http://powertoe.wordpress.com/2010/08/28/controlling-registry-acl-permissions-with-powershell/
function enable-privilege {
param(
## The privilege to adjust. This set is taken from
## http://msdn.microsoft.com/en-us/library/bb530716(VS.85).aspx
[ValidateSet(
"SeAssignPrimaryTokenPrivilege", "SeAuditPrivilege", "SeBackupPrivilege",
"SeChangeNotifyPrivilege", "SeCreateGlobalPrivilege", "SeCreatePagefilePrivilege",
"SeCreatePermanentPrivilege", "SeCreateSymbolicLinkPrivilege", "SeCreateTokenPrivilege",
"SeDebugPrivilege", "SeEnableDelegationPrivilege", "SeImpersonatePrivilege", "SeIncreaseBasePriorityPrivilege",
"SeIncreaseQuotaPrivilege", "SeIncreaseWorkingSetPrivilege", "SeLoadDriverPrivilege",
"SeLockMemoryPrivilege", "SeMachineAccountPrivilege", "SeManageVolumePrivilege",
"SeProfileSingleProcessPrivilege", "SeRelabelPrivilege", "SeRemoteShutdownPrivilege",
"SeRestorePrivilege", "SeSecurityPrivilege", "SeShutdownPrivilege", "SeSyncAgentPrivilege",
"SeSystemEnvironmentPrivilege", "SeSystemProfilePrivilege", "SeSystemtimePrivilege",
"SeTakeOwnershipPrivilege", "SeTcbPrivilege", "SeTimeZonePrivilege", "SeTrustedCredManAccessPrivilege",
"SeUndockPrivilege", "SeUnsolicitedInputPrivilege")]
$Privilege,
## The process on which to adjust the privilege. Defaults to the current process.
$ProcessId = $pid,
## Switch to disable the privilege, rather than enable it.
[Switch] $Disable
## Taken from P/Invoke.NET with minor adjustments.
$definition = @'
using System;
using System.Runtime.InteropServices;
public class AdjPriv
[DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]
internal static extern bool AdjustTokenPrivileges(IntPtr htok, bool disall,
ref TokPriv1Luid newst, int len, IntPtr prev, IntPtr relen);
[DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]
internal static extern bool OpenProcessToken(IntPtr h, int acc, ref IntPtr phtok);
[DllImport("advapi32.dll", SetLastError = true)]
internal static extern bool LookupPrivilegeValue(string host, string name, ref long pluid);
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct TokPriv1Luid
public int Count;
public long Luid;
public int Attr;
internal const int SE_PRIVILEGE_ENABLED = 0x00000002;
internal const int SE_PRIVILEGE_DISABLED = 0x00000000;
internal const int TOKEN_QUERY = 0x00000008;
internal const int TOKEN_ADJUST_PRIVILEGES = 0x00000020;
public static bool EnablePrivilege(long processHandle, string privilege, bool disable)
bool retVal;
TokPriv1Luid tp;
IntPtr hproc = new IntPtr(processHandle);
IntPtr htok = IntPtr.Zero;
retVal = OpenProcessToken(hproc, TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, ref htok);
tp.Count = 1;
tp.Luid = 0;
if(disable)
tp.Attr = SE_PRIVILEGE_DISABLED;
else
tp.Attr = SE_PRIVILEGE_ENABLED;
retVal = LookupPrivilegeValue(null, privilege, ref tp.Luid);
retVal = AdjustTokenPrivileges(htok, false, ref tp, 0, IntPtr.Zero, IntPtr.Zero);
return retVal;
$processHandle = (Get-Process -id $ProcessId).Handle
$type = Add-Type $definition -PassThru
$type[0]::EnablePrivilege($processHandle, $Privilege, $Disable)
enable-privilege SeTakeOwnershipPrivilege
$key = [Microsoft.Win32.Registry]::LocalMachine.OpenSubKey("SOFTWARE\powertoe",[Microsoft.Win32.RegistryKeyPermissionCheck]::ReadWriteSubTree,[System.Security.AccessControl.RegistryRights]::takeownership)
$acl = $key.GetAccessControl()
$me = [System.Security.Principal.NTAccount]"t-alien\tome"
$acl.SetOwner($me)
$key.SetAccessControl($acl)
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