Roasting
Offline cracking of Kerberos tickets and pre-auth material
Theory
"Roasting" attacks abuse the fact that parts of the Kerberos exchange are encrypted with a key derived from an account's password. An attacker who can obtain that encrypted material can take it offline and crack it, without any failed-logon events on the target.
The variants differ in which message is harvested and what is required to get it:
| Attack | Harvests | Requires |
|---|---|---|
| Kerberoasting | Service ticket (TGS-REP) encrypted with the service account key | valid domain credentials, target SPN or SAN |
| ASREProasting | AS-REP encrypted with the user key | no credentials; target must have pre-auth disabled |
| ASREQroasting | AS-REQ timestamp encrypted with the user key | a MitM position on the client |
Accounts with human-set passwords are the useful targets. Machine accounts have long random passwords and are not realistically crackable.