Get the Whitepaper called Attacking and fixing the Microsoft Windows Kerberos Login Service.
You can download it from the following link: https://packetstormsecurity.com/files/download/92760/m0t-krb5-08-2010.pdf
Source: https://packetstormsecurity.com/files/92760/Attacking-And-Fixing-The-Microsoft-Windows-Kerberos-Login-Service.html