Adversaries may "pass the hash" using stolen password hashes to move laterally within an environment, bypassing normal system access controls. Pass the hash (PtH) is a method of authenticating as a user without having access to the user's clear text password. This method bypasses standard authentication steps that require a clear text password, moving directly into the portion of the authentication that uses the password hash.
When performing PtH, valid password hashes for the account being used are captured using a Credential Access technique. Captured hashes are used with PtH to authenticate as that user. Once authenticated, PtH may be used to perform actions on local or remote systems.
Adversaries may also use stolen password hashes to "overpass the hash." Similar to PtH, this involves using a password hash to authenticate as a user but also uses the password hash to create a valid Kerberos ticket. This ticket can then be used to perform Pass the Ticket attacks.
In the following scenario we have compromised a Windows 2019 member server SRV01.Security.local and escalated privileges to the local administrator account. We then dumped credentials from LSASS memory using Mimikatz and have obtained the NTLM password hash for the Domain Administrator "Moe".
LSASS Memory Credential Dumping
We are working as the local administrator on SRV01 so we are unable to perform administrative function on the Domain.
As we have the NTLM hash for the Domain Administrator "Moe" we are able to use Mimikatz to Pass-The-Hash to a new process such as PowerShell.
By doing so we are able to then use the newly spawned PowerShell process to perform domain administrative functions.
Under our local administrator account and as expected, we are unable to create a new domain user.
Next we Pass-The-Hash for the Domain Administrator Moe:
Which opens a new PowerShell process for us. Where, we still notice we are running as the local administrator on the member server SRV01 however, we now have the ability to work as the Domain Administrator Moe and create a new domain user and add them to the "Domain Admins" group.
Mitigation
Enable Windows Credential Guard
Deploy Microsoft LAPS
Disable LM/NTLM authentication in the environment
Reduce amount of cached logon passwords stored
Limit administrative users in the domain / locally.
Further Reading
Mitigating Pass-the-Hash (PtH) Attacks and Other Credential Theft Techniques v2:
