Adversaries may use password cracking to attempt to recover usable credentials, such as plaintext passwords, when credential material such as password hashes are obtained. OS Credential Dumping can be used to obtain password hashes, this may only get an adversary so far when Pass the Hash is not an option. Further, adversaries may leverage Data from Configuration Repository in order to obtain hashed credentials for network devices.
Techniques to systematically guess the passwords used to compute hashes are available, or the adversary may use a pre-computed rainbow table to crack hashes. Cracking hashes is usually done on adversary-controlled systems outside of the target network. The resulting plaintext password resulting from a successfully cracked hash may be used to log into systems, resources, and services in which the account has access.
APT3 has been known to brute force password hashes to be able to leverage plain text credentials.
APT41 performed password brute-force attacks on the local admin account.
Dragonfly has dropped and executed tools used for password cracking, including Hydra and CrackMapExec.
FIN6 has extracted password hashes from ntds.dit to crack offline.
Net Crawler uses a list of known credentials gathered through credential dumping to guess passwords to accounts as it spreads throughout a network.
During Night Dragon, threat actors used Cain & Abel to crack password hashes.
Use multi-factor authentication. Where possible, also enable multi-factor authentication on externally facing services.
Refer to NIST guidelines when creating password policies. 
|ID||Data Source||Data Component||Detects|
|DS0015||Application Log||Application Log Content||
Monitor authentication logs for system and application login failures of Valid Accounts. It is difficult to detect when hashes are cracked, since this is generally done outside the scope of the target network. Consider focusing efforts on detecting other adversary behavior used to acquire credential materials, such as OS Credential Dumping or Kerberoasting.
|DS0002||User Account||User Account Authentication||
Monitor for many failed authentication attempts across various accounts that may result from password spraying attempts. It is difficult to detect when hashes are cracked, since this is generally done outside the scope of the target network. (ex: Windows EID 4625 or 5379)