Threat actors use these ticket-granting services to crack passwords and retrieve them on plaintext.In Kerberoasting, encryption RC4_HMAC is susceptible to brute-force attacks. SPNs are used by Kerberos authentication to associate a service instance with a service logon account. Service principal name ( SPN) is a unique identifier of a service instance. Kerberoasting attacks abuse the TGT ( ticket-granting tickets ) to request SPN ( service principal name ) within Active Directory domains. Therefore successful authentication happens mutual to establish a access for relevant users.Whenever user connect to other specific application servers, present TGT ticket is sent to application server to authenticate as ( AS-REQ ), Destination server open and validate the users TGT tickets using the NTLM password hash.There are 3 possible values for this policy:ĭisabled (default): NO PAC validation will be done at all.Įnabled: If PAC Validation fails, the PAC information is used and the user login is allowed.Įnforced: If PAC Validation fails, the PAC information is discarded and the user login is denied.Īlso Read : Soc Interview Questions and Answers – CYBER SECURITY ANALYST When users use their Kerberos tickets to authenticate to other systems, the PAC ( Privilege Attribute Certificate ) can be read and used to determine their level of privileges without reaching out to the domain controller to query for that information.TGT is sent back to the user’s workstation in encrypted format as an authentication response ( AS-REP ).Domain controller validates the user’s group policies and creates a valid TGT for the authentication.) will be created for the user’s password, TGT ( Ticket Granting Ticket ) will be sent to KDC Server ( Kerberos Key Distribution Center ) as authentication request ( AS-REQ ) Whenever the user tries to login with his/her username and password, NTLM hash ( NT LAN Manager is a suite of Microsoft security protocols intended to provide authentication, integrity, and confidentiality to users.To understand the Kerberos attack, you must know the authentication flow with the domain controller for better understanding and visibility for faster incident response. It is designed to provide strong authentication for client/server applications by using secret-key cryptography. Kerberos is a network authentication protocol.
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