T1110 - Brute Force

Adversaries may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained. Without knowledge of the password for an account or set of accounts, an adversary may systematically guess the password using a repetitive or iterative mechanism. Brute forcing passwords can take place via interaction with a service that will check the validity of those credentials or offline against previously acquired credential data, such as password hashes.

Brute forcing credentials may take place at various points during a breach. For example, adversaries may attempt to brute force access to Valid Accounts within a victim environment leveraging knowledge gathered from other post-compromise behaviors such as OS Credential Dumping, Account Discovery, or Password Policy Discovery. Adversaries may also combine brute forcing activity with behaviors such as External Remote Services as part of Initial Access.

Atomic Tests:

Currently, no tests are available for this technique.

Detection

Monitor authentication logs for system and application login failures of Valid Accounts. If authentication failures are high, then there may be a brute force attempt to gain access to a system using legitimate credentials. Also 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.

Shield Active Defense

System Activity Monitoring

Collect system activity logs which can reveal adversary activity.

Capturing system logs can show logins, user and system events, etc. Collecting this data and potentially sending it to a centralized location can help reveal the presence of an adversary and the actions they perform on a compromised system.

Opportunity

There is an opportunity to create a detection with a moderately high probability of success.

Use Case

A defender can monitor for user login activity that may reveal an adversary leveraging brute force techniques.

Procedures

Ensure that systems capture and retain common system level activity artifacts that might be produced. Monitor Windows systems for event codes that reflect an adversary changing passwords, adding accounts to groups, etc.