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MITRE ATT&CK · T1110

Brute Force

MITRE · cited in 9 of our lessons

Explanation

What attackers do. Attackers try to get into accounts by guessing passwords, trying common passwords across many accounts, reusing leaked credentials, or cracking stolen password hashes. This serves the Credential Access tactic.

How to defend. Enforce MFA, block common and breached passwords, and use smart account lockout that limits attackers without locking users out. Disable legacy authentication protocols that bypass MFA. Monitor identity provider, VPN and directory logs for failed logins across many accounts.

Signs to look for. Look for many failed logins from one source, a few failures each across many accounts, successful logins after failures, and authentication against legacy protocols. A common gap is attackers spreading attempts slowly across sources to stay under thresholds. Password spraying against cloud services is common, so check sign-in logs for one source touching many accounts.

Open the technique on MITRE ATT&CK
The official text
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. If an adversary guesses the correct password but fails to login to a compromised account due to location-based conditional access policies, they may change their infrastructure until they match the victim’s location and therefore bypass those policies.

© The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation (MITRE ATT&CK®).

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