Thursday, April 26, 2012

Decoding AD ACL's (Powershell)

Today I was looking at a deep dive video on creating modules and found out about the BSonPosh module.  This contains some interesting commandlets, one of which is similar to some of the work I have been doing lately related to managing AD object ACL's.  The commandlets for get-adacl in this module are similar to what you can get with the Microsoft AD module using get-acl pointing to the AD PSDrive.  The thing that makes BSOnPosh great in comparison is that it works great on a multi-domain environment, and you don't need to go out of your way to point to 2008 servers if you have a mixed environment.  In any case, if you look at my previous post related to decoding GUID's in ACL's by converting GUID's into an ldap searchable format, we can use this to extend the work done by BSonPosh.  First, lets look again at what the acl entries look like:

ActiveDirectoryRights : CreateChild, DeleteChild
InheritanceType : None
ObjectType : bf967aa8-0de6-11d0-a285-00aa003049e2
InheritedObjectType : 00000000-0000-0000-0000-000000000000
ObjectFlags : ObjectAceTypePresent
AccessControlType : Allow
IdentityReference : S-1-5-32-550
IsInherited : False
InheritanceFlags : None
PropagationFlags : None

Here, you can see many of the enumerations are decoded into text, but we have guid's and SID's that may show up without translation.  With BSonPosh, there is a function for converting SID's already, though in this case I'm modifying it to handle SID's that do not translate with that code.  Combining that with another helper function to decode the GUID's to the ldap display attribute listed in the schema,  you can get a result that is more readable like this:

Get-ADACL -distinguishedname "dc=contoso,dc=com" | convert-adacl

ActiveDirectoryRights : ReadProperty, WriteProperty, Delete
InheritanceType          : Descendents
ObjectType                : msRTCSIP-UserPolicies
InheritedObjectType   : user
ObjectFlags                : ObjectAceTypePresent, InheritedObjectAceTypePresent
AccessControlType    : Allow
IdentityReference        : CONTOSO\RTCDomainUserAdmins
IsInherited                   : False
InheritanceFlags          : ContainerInherit
PropagationFlags        : InheritOnly

Below is the code.  One function was changed (ConvertTO-Name).  The rest is added to BSActiveDirectory.psm1.  It is important to note, that this conversion function creates its own custom PSobject, so it is not longer an ACL that you can play with and try to write back.  This was more designed for auditing purposes.

#region Convert-ADACL 

function Convert-ADACL
            Translates the AD Object ACL to a more readable format by converting SID and GUID values to text
            Translates the AD Object ACL to a more readable format by converting SID and GUID values to tex
        .Parameter ACL
            ACL Object to Apply

  Begin {
   $results = @()
  process {
   if ($_.ActiveDirectoryRights -eq "ExtendedRight") {
    $myresult = New-Object PSobject -Property @{
     ActiveDirectoryRights = $_.ActiveDirectoryRights
     InheritanceType = $_.InheritanceType
     ObjectType = Convert-GUIDToName -guid $_.objecttype -extended
     InheritedObjectType = Convert-GUIDToName -guid $_.inheritedobjecttype
     ObjectFlags = $_.ObjectFlags
     AccessControlType = $_.accesscontroltype
     IdentityReference = ConvertTo-Name -sid $_.identityReference
     IsInherited = $_.isinherited
     InheritanceFlags = $_.InheritanceFlags
     PropagationFlags = $_.PropagationFlags
   } else {
          $myresult = New-Object PSobject -Property @{
     ActiveDirectoryRights = $_.ActiveDirectoryRights
     InheritanceType = $_.InheritanceType
     ObjectType = Convert-GUIDToName -guid $_.objecttype
     InheritedObjectType = Convert-GUIDToName -guid $_.inheritedobjecttype
     ObjectFlags = $_.ObjectFlags
     AccessControlType = $_.accesscontroltype
     IdentityReference = ConvertTo-Name -sid $_.identityReference
     IsInherited = $_.isinherited
     InheritanceFlags = $_.InheritanceFlags
     PropagationFlags = $_.PropagationFlags
   $results += $Myresult

  end {
   $results |Select-Object ActiveDirectoryRights,InheritanceType,ObjectType,InheritedObjectType,ObjectFlags,`

#region ConvertTo-Name 

function ConvertTo-Name
 Write-Verbose $sid
 try {
     $ID = New-Object System.Security.Principal.SecurityIdentifier($sid)
     $User = $ID.Translate( [System.Security.Principal.NTAccount])
 } catch {
  switch($sid) {
   "S-1-0" { "Null Authority" }
   "S-1-0-0" { "Nobody" }
   "S-1-1" {"World Authority" }
   "S-1-1-0" { "Everyone" }
   "S-1-2" { "Local Authority" }
   "S-1-2-0" { "Local" }
   "S-1-2-1" { "Console Logon" }
   "S-1-3" { "Creator Authority" }
   "S-1-3-0" { "Creator Owner" }
   "S-1-3-1" { "Creator Group" }
   "S-1-3-4" { "Owner Rights" }
   "S-1-5-80-0" {"All Services" }
   "S-1-4" { "Non Unique Authority" }
   "S-1-5" { "NT Authority" }
   "S-1-5-1" { "Dialup" }
   "S-1-5-2" { "Network" }
   "S-1-5-3" { "Batch" }
   "S-1-5-4" { "Interactive" }
   "S-1-5-6" { "Service" }
   "S-1-5-7" { "Anonymous" }
   "S-1-5-9" { "Enterprise Domain Controllers"}
   "S-1-5-10" { "Self" }
   "S-1-5-11" { "Authenticated Users" }
   "S-1-5-12" { "Restricted Code" }
   "S-1-5-13" { "Terminal Server Users" }
   "S-1-5-14" { "Remote Interactive Logon" }
   "S-1-5-15" { "This Organization" }
   "S-1-5-17" { "This Organization" }
   "S-1-5-18" { "Local System" }
   "S-1-5-19" { "NT Authority Local Service" }
   "S-1-5-20" { "NT Authority Network Service" }
   "S-1-5-32-544" { "Administrators" }
   "S-1-5-32-545" { "Users"}
   "S-1-5-32-546" { "Guests" }
   "S-1-5-32-547" { "Power Users" }
   "S-1-5-32-548" { "Account Operators" }
   "S-1-5-32-549" { "Server Operators" }
   "S-1-5-32-550" { "Print Operators" }
   "S-1-5-32-551" { "Backup Operators" }
   "S-1-5-32-552" { "Replicators" }
   "S-1-5-32-554" { "Pre-Windows 2000 Compatibility Access"}
   "S-1-5-32-555" { "Remote Desktop Users"}
   "S-1-5-32-556" { "Network Configuration Operators"}
   "S-1-5-32-557" { "Incoming forest trust builders"}
   "S-1-5-32-558" { "Performance Monitor Users"}
   "S-1-5-32-559" { "Performance Log Users" }
   "S-1-5-32-560" { "Windows Authorization Access Group"}
   "S-1-5-32-561" { "Terminal Server License Servers"}
   "S-1-5-32-561" { "Distributed COM Users"}
   "S-1-5-32-569" { "Cryptographic Operators" }
   "S-1-5-32-573" { "Event Log Readers" }
   "S-1-5-32-574" { "Certificate Services DCOM Access" }
   "S-1-5-32-575" { "RDS Remote Access Servers" }
   "S-1-5-32-576" { "RDS Endpoint Servers" }
   "S-1-5-32-577" { "RDS Management Servers" }
   "S-1-5-32-575" { "Hyper-V Administrators" }
   "S-1-5-32-579" { "Access Control Assistance Operators" }
   "S-1-5-32-580" { "Remote Management Users" }
   default {$sid}

#region Convert-GUIDToName

 #helper module to convert schema GUID's to readable names

function Convert-GUIDToName
 $guidval = [Guid]$guid
 $bytearr = $guidval.tobytearray()
    $bytestr = ""
 foreach ($byte in $bytearr) {
          $str = "\" + "{0:x}" -f $byte
          $bytestr += $str
 if ($extended) {
  #for extended rights, we can check in the configuration container
  $de = new-object directoryservices.directoryentry("LDAP://" + ([adsi]"LDAP://rootdse")
  $ds = new-object directoryservices.directorysearcher($de)
  $ds.filter = "(rightsguid=$guid)"
  $result = $ds.findone()
 } else {
  #Search schema for possible matches for this GUID
  $de = new-object directoryservices.directoryentry("LDAP://" + ([adsi]"LDAP://rootdse")
  $ds = new-object directoryservices.directorysearcher($de)
  $ds.filter = "(|(schemaidguid=$bytestr)(attributesecurityguid=$bytestr))"
  $result = $ds.findone()
 if ($result -eq $null) {
 } else {
  if ($extended) {
  } else {

Update: 1/29/2013

Just an additional note. Since you need distinguishednames for the commandlets, this can be a pain at times. If you like to use dsquery for quick and short results you can pipe these in, however you need to deal with the quotations that are put around the dsquery output. Example:

dsquery group -name Mygroup | foreach {$_.replace("`"","")} | 
get-adacl | where {$_.isinhertied -eq $false} |convert-adacl

Thursday, April 19, 2012

Powershell overlapping pipeline problem

During the recent Microsoft 2012 scripting games, I encountered an interesting problem which really threw me off for a few hours. When trying to link up WMI results with registry entries in the Advanced 8 event, I ended up with a lot of Get-ItemProperty failures, where the values being read in my registry access where actually results from my WMI lookups. Here is a sample of the code

function get-physicalphysical {
     param(  [parameter(position=0)][string]$nicGUID   )
    $vals = Get-ChildItem hklm:"\System\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}" |
          get-itemproperty -name $ | where {$_.netcfginstanceid -match $nicGuid}
    if ($vals.characteristics -eq 0x84) { return $true } else { return $false }

$nics = Get-WmiObject -Class Win32_NetworkAdapter -Filter "PhysicalAdapter = True" |
where {get-physicalphysical $($_.guid)}

So we have GWMI for network adapters piped to a function called get-physicalphysical.  The guid of the WMI network adapter result is searched in the registry for lower level details that are not available via WMI.  The error we get is something like this (repeating many times and for different adapter names)

Get-ItemProperty : Property Intel(R) 82567LM Gigabit Network Connection does not exist at path HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}\0000.
At line:11 char:25
+         get-itemproperty <<<<  -name $ | where {$_.netcfginstanceid -ma
tch $nicGuid}
    + CategoryInfo          : InvalidArgument: (Intel(R) Connect
   ion:String) [Get-ItemProperty], PSArgumentException
    + FullyQualifiedErrorId : System.Management.Automation.PSArgumentException

In this case, the WMI results have a property called Name, and the entries in the registry that we were looking at also have a value for Name.  What we want is the name of the registry key that contains the configurations for the adapter.  But with the use of two pipelines, it appears that the $_ referenced in the pipeline within the function is accessing the pipeline $_ from outside of the function.  I'm not expert in low level powershell details and how the pipeline works, but after playing around a bit with trying to scope the $_ variable, and eventually reading the about_functions help, I found that you can scope a function.  By scoping the function and the $_ variable within it (using the same scope), I was able to separate the two pipelines and accomplish what I was hoping for.  You can see the full code at the entry script.