Adversaries may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained.(Citation: TrendMicro Pawn Storm Dec 2020) 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.(Citation: Dragos Crashoverride 2018) 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](https://attack.mitre.org/techniques/T1078) within a victim environment leveraging knowledge gathered from other post-compromise behaviors such as [OS Credential Dumping](https://attack.mitre.org/techniques/T1003), [Account Discovery](https://attack.mitre.org/techniques/T1087), or [Password Policy Discovery](https://attack.mitre.org/techniques/T1201). Adversaries may also combine brute forcing activity with behaviors such as [External Remote Services](https://attack.mitre.org/techniques/T1133) 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.(Citation: ReliaQuest Health Care Social Engineering Campaign 2024)