How to run commands using SYSTEM account

INTRODUCTION

This is a process I use whenever I get an “Access Denied” message. One example of this is when I do not have access to SQL Server directly, only administrative rights to the actual server.

PROCESS

1) Download PsExec which is part of the PsTools suite

2) Extract PsTools.zip to a convenient location. I usually copy PsExec.exe to the System32 folder. This allows PsExec.exe to be executed from any folders without specifying the full path.

3) Execute the following command

PsExec.exe -s -i -d CMD.exe

4) From within this new command prompt, everything you open will open as the SYSTEM account.

EXAMPLES

Viewing NT Secrets

Open Regedit.exe and you will be able to see content of HKEY_LOCAL_MACHINE\SECURITY

  • This allows you to view passwords that were stored as NT Secrets

Opening SQL Server Management Studio as SYSTEM

Open SQL Management Studio and you will be able to log on with SYSTEM

  • This allows you to access SQL without directly having been granted SQL right yet you have administrative rights to SQL Server

You will be able to browse to any folder that only allows SYSTEM account

  • You can export permissions with SetACL/ICACLS to folders that administrators group might have been removed on
  • Kill processes that give error Access Denied when you try to terminate it with normal Administrator rights

WinDirStat/TreeSize etc.

Running something like TreeSize as SYSTEM will actually give you a better view and understanding of what is using space because you will get less access denials

Some others…

  • Simulate GPO start scripts
  • Simulate GPO based MSI installation
  • Diagnose why scheduled tasks that run as SYSTEM don’t run as intended
  • Start/stop protected services

CONCLUSION

Using this process, (or one similar) will allow you to start processes as the SYSTEM account allowing you to access parts of files system, registry and application not accessible with normal Administrative rights.

How to extract hashes from IFM backup

Auditing domain password hashes is a commonly overlooked but critical requirement to ensuring secure passwords practices are followed.
Methods exist to extract hashes directly for a live domain however this article describes a process to extract user data, including hashes from an IFM backup.

1) Overview

Overpermission and weak/reused passwords are probably the most common security issues found in Active Directory. To address the password issues, it is important to do regular password audits, to address over permissions, see my article about Active Directory delegation.

 

2) Password Hashes

Passwords are stored in Active Directory (NTDS.dit encrypted with a boot key) as an unsalted MD4 hash and as such, to check for password reuse it is a simple case of checking for duplicate hashes in the extracted hashes list.

 

Finding weak passwords are a little trickier. You need to lookup hashes against a rainbow table to ensure you do not have any weak/compromised hashes within your environment.

 

Both of these are out-of-scope for this article, this article focuses on extracting password hashes.

 

3) Extracting Password Hashes

a) On a Domain Controller

 

Start an elevated command prompt and run:

 

ntdsutil
activate instance ntds
ifm
create sysvol full C:\Temp\Backups\IFM\

 

Command Output




IFM Files

 

b) On Administrative Computer

 

Copy the IFM folder and run the following PowerShell script elevated (just copy and paste):

 

//Download DSInternals from PowerShell Gallery https://www.powershellgallery.com/packages/DSInternals
Save-Module -Name DSInternals -path 'C:\temp\DSInternals'


//Install DSInternals
Install-Module -Name DSInternals


//Import DSInternals Module
Import-Module DSInternals


//Get Boot Key from Registry section of the IFM. If Boot Key is blank, Get-ADDBAccount will still return usernames
$key = Get-BootKey -SystemHivePath 'C:\Temp\Backups\IFM\registry\SYSTEM'


//Store objects data
$hashes = Get-ADDBAccount -All -DBPath 'C:\Temp\Backups\IFM\Active Directory\ntds.dit' -BootKey $key


//Convert object data to the desired format
$hashes | Format-Custom -View Ophcrack | Out-File C:\Temp\Backups\Hashes.txt

 

Hashes.txt File

 

 

Weak Passwords Found (Getting password from hashes out-of-scope for this article)