Final answer:
Attackers can compromise Kerberos-based authentication systems by creating forged 'golden' or 'silver' tickets using tools like Mimikatz, which extracts credentials from LSASS. These credentials can enable pass-the-hash or pass-the-ticket attacks. Defenses include security best practices, multi-factor authentication, and up-to-date security measures.
Step-by-step explanation:
Kerberos is a network authentication protocol designed to provide strong authentication for client-server applications by using secret-key cryptography. A well-known vulnerability in Kerberos-based authentication systems is the ability to create "golden" and "silver" tickets. These are forged Kerberos tickets allowing attackers to impersonate any user, even administrators, and gain unauthorized access to network resources.
Tools like Mimikatz exploit weaknesses in the Windows security environment. Its sekurlsa module can extract credential information, such as plaintext passwords and Kerberos tickets, from the Local Security Authority Subsystem Service (LSASS). With these credentials or tickets, an attacker can perform pass-the-hash or pass-the-ticket attacks to access other computers on the network without needing the user's actual password.
Preventing such attacks involves several steps, including the use of strong, unique passwords, regular password changes, enabling advanced security features like account lockout policies, and monitoring for unusual activity. It is also essential to keep systems updated with the latest security patches and to educate users on the importance of maintaining good security practices to defend against such threats. Using multi-factor authentication can also provide a layer of security beyond the Kerberos protocol.
While Mimikatz cannot be used "over the wire" to directly extract information, it can be deployed onto a compromised machine to extract sensitive data which can then enable further attacks. Organizations must be diligent in their defense against such tools by ensuring that the least privilege principle is enforced, implementing network segmentation, and maintaining an effective incident response plan.