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.

Positive Technologies products that cover the technique

MaxPatrol SIEM knowledge base

bruteforce: PT-CR-1774: Reason_Account_Blocked: A user account was locked

Subtechniques

Detection

IDDS0015Data source and componentApplication Log: Application Log ContentDescription

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.

IDDS0002Data source and componentUser Account: User Account AuthenticationDescription

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.

IDDS0017Data source and componentCommand: Command ExecutionDescription

Monitor executed commands and arguments that may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained.

Mitigation

IDM1027NamePassword PoliciesDescription

Refer to NIST guidelines when creating password policies.

IDM1018NameUser Account ManagementDescription

Proactively reset accounts that are known to be part of breached credentials either immediately, or after detecting bruteforce attempts.

IDM1036NameAccount Use PoliciesDescription

Set account lockout policies after a certain number of failed login attempts to prevent passwords from being guessed. Too strict a policy may create a denial of service condition and render environments un-usable, with all accounts used in the brute force being locked-out. Use conditional access policies to block logins from non-compliant devices or from outside defined organization IP ranges.

IDM1032NameMulti-factor AuthenticationDescription

Use multi-factor authentication. Where possible, also enable multi-factor authentication on externally facing services.