SHREE LEARNING ACADEMY

An attack called "Pass the hash" has the potential to enable unauthorized access to a system or network by exploiting the authentication of an authorized user, without requiring knowledge or possession of the victim's actual login credentials. The primary target of this attack is Windows systems, which store a collection of cached credentials (referred to as "hash" in the attack name and also known as the authentication token) on client machines for the Windows domains that the user has authenticated with.

If the domain controllers that handle authentication are unavailable during a subsequent login attempt, the cached credentials stored on the local system are utilized to grant the user access to both the network and the local system. Under these circumstances, the cached credentials are utilized, and when the domain controllers are restored, the user is deemed to have been authenticated correctly by the domain controllers, as the user gained access via the cached credentials from their previous successful domain login. Despite Microsoft's efforts to enhance the security of this process, hackers persist in exploiting this fault-tolerant aspect of Windows operating systems.

The attacker retrieves the cached credentials from the victim's system Registry and leverages them on a rogue domain client. This could deceive the domain controller into recognizing the attacker as an authorized user, even though the attacker did not actually participate in the authentication process.

Preventive Measures

To mitigate this attack, one can disable cached credentials, demand network-level authentication. Employing Restricted Admin mode is also an effective defensive measure. Additionally, implementing two-factor authentication can prevent this type of attack in some instances. You can also enforce the use of NTLMv2 (while disabling NTLM and LM).