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Potential Password Spraying of Microsoft 365 User Accountsedit

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: 5 minutes

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

Maximum alerts per execution: 100

Tags:

  • Elastic
  • Cloud
  • Microsoft 365
  • Continuous Monitoring
  • SecOps
  • Identity and Access

Version: 5 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 8.1.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positivesedit

Automated processes that attempt to authenticate using expired credentials and unbounded retries may lead to false positives.

Investigation guideedit

## Config

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

Rule queryedit

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

Threat mappingedit

Framework: MITRE ATT&CKTM

Rule version historyedit

Version 5 (8.1.0 release)

  • Updated query, changed from:

    event.dataset:o365.audit and event.provider:(Exchange or
AzureActiveDirectory) and event.category:authentication and
event.action:("UserLoginFailed" or
"PasswordLogonInitialAuthUsingPassword") and event.outcome:failure
Version 4 (7.14.0 release)

  • Updated query, changed from:

    event.dataset:o365.audit and event.provider:AzureActiveDirectory and
event.category:authentication and event.action:UserLoginFailed and
event.outcome:failure
Version 3 (7.13.0 release)
  • Formatting only
Version 2 (7.12.0 release)
  • Formatting only
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