Brute Force: Password Cracking
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 is used to obtain password hashes, this may only get an adversary so far when Pass the Hash is not an option. 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.
Use multi-factor authentication. Where possible, also enable multi-factor authentication on externally facing services.
Refer to NIST guidelines when creating password policies. 
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.
- Wikipedia. (n.d.). Password cracking. Retrieved December 23, 2015.
- Grassi, P., et al. (2017, December 1). SP 800-63-3, Digital Identity Guidelines. Retrieved January 16, 2019.
- Cylance. (2014, December). Operation Cleaver. Retrieved September 14, 2017.
- US-CERT. (2018, March 16). Alert (TA18-074A): Russian Government Cyber Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved June 6, 2018.
- US-CERT. (2017, October 20). Alert (TA17-293A): Advanced Persistent Threat Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved November 2, 2017.
- Kali. (2014, February 18). THC-Hydra. Retrieved November 2, 2017.
- Korban, C, et al. (2017, September). APT3 Adversary Emulation Plan. Retrieved January 16, 2018.
- Fraser, N., et al. (2019, August 7). Double DragonAPT41, a dual espionage and cyber crime operation APT41. Retrieved September 23, 2019.