Pass the hash
Pass the hash is a term in penetration testing that recycles cached credentials from a compromised computer to log onto other systems that share the same password on the same or similar account. This method avoids having to brute force the passwords by hashing all possible passwords and comparing them to the found hashes.
On Windows systems, for example, login passwords are never sent cleartext over the wire. Instead, they are provided to the requesting system, such as a domain controller, as a hash in a response of a challenge-response scheme. To enable users to log on to a Windows computer even when the server's offline, i.e. without access to the domain controller, Windows computers may cache the password hashes on the local systems if they are configured in this way.[citation needed]
Penetration testers who compromise a computer can then collect these cached hashes from the Security Accounts Manager (SAM) or read password hashes from the memory of system processes such as lsass.exe that are responsible for managing credentials. Once they are in the penetration testing solution, such as Metasploit[1], they can use create new processes that run under the compromised account by injecting the stolen hash into the process, and thereby gain access to other resources.