Potential Password Spraying of Microsoft 365 User Accounts

Identifies a high number (25) of failed Microsoft 365 user authentication attempts from a single IP address within 30 minutes, which could be indicative of a password spraying attack. An adversary may attempt a password spraying attack to obtain unauthorized access to user accounts.

Rule type: threshold

Rule indices:

filebeat-*
logs-o365*

Severity: high

Risk score: 73

Runs every: 5m

Searches indices from: now-30m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

Elastic
Cloud
Microsoft 365
Continuous Monitoring
SecOps
Identity and Access

Version: 9

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

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## Setup

The Office 365 Logs Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule.

Rule query

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event.dataset:o365.audit and event.provider:(Exchange or AzureActiveDirectory) and event.category:authentication and
event.action:("UserLoginFailed" or "PasswordLogonInitialAuthUsingPassword")

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Credential Access
- ID: TA0006
- Reference URL: https://attack.mitre.org/tactics/TA0006/
Technique:
- Name: Brute Force
- ID: T1110
- Reference URL: https://attack.mitre.org/techniques/T1110/

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