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Showing posts with the label Kerberos

MITRE ATT&CK - Kerberos Vulnerabilities and Security

From the previous post, the summary of Kerberos authentication process is as below: For the initial authentication, the user’s client machine sends a request to the KDC  Authentication Service (AS) . The request includes details like the user’s username, and the date and time. All information except the username is encrypted using the hash of the user’s password. The KDC AS uses the username to look up its copy of the user’s password hash and uses it to decrypt the rest of the request. If the decryption is successful, that means the client used the correct password hash and the user has successfully authenticated. Once the user is authenticated, the KDC AS sends the user’s client a  ticket granting ticket   (TGT) . The TGT includes a unique session key and a timestamp that specifies how long that session is valid (normally 8 or 10 hours). Importantly, before sending the TGT, the KDC encrypts it using the password hash for a special account, the  KRBTGT account.  That password hash is s

MITRE ATT&CK - Understanding Kerberos (for Golden Ticket Attack)

Kerberos = Network Authentication Protocol used by AD environments Provides authentication by issuing tickets to authenticate users and allow them access to the services Tickets are distibuted by KDC (Key Distribution Center), which is typically a Domain Controller (DC) During initial authentication, a TGT (Ticket Granting Ticket) is a ticket asigned to a user by KDC. TGT is later used to authenticate the user to the KDC in order to request a service ticket from TGS (Ticket Granting Service). Service tickets are granted for authentication against services. List of steps / negotiations for Kerberos authentication (of the user with the service): The user requests  (AS-REQ)  a TGT from the KDC and the KDC verifies and validates the credentials and user information. This request if often done automatically at login. After authenticating the user, the KDC sends an encrypted TGT back to the requester  (AS-REP) . The user presents the TGT to the DC and requests a TGS  (TGS-REQ) . The TGS is e