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InformationalSplunk security contentRod Soto +1

O365 Excessive Authentication Failures Alert

The following analytic identifies an excessive number of authentication failures, including failed attempts against MFA prompt codes. It uses data from the `o365_management_activity` dataset, focusing on events where…

Description

The following analytic identifies an excessive number of authentication failures, including failed attempts against MFA prompt codes. It uses data from the `o365_management_activity` dataset, focusing on events where the authentication status is marked as failure. This behavior is significant as it may indicate a brute force attack or an attempt to compromise user accounts. If confirmed malicious, this activity could lead to unauthorized access, data breaches, or further exploitation within the environment.

Detection logic

Detection requirements

Platform
ContainersESXiIaaSIdentity ProviderLinuxmacOSNetwork DevicesOffice SuiteSaaSWindows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Known benign triggers

  • The threshold for alert is above 10 attempts and this should reduce the number of false positives.

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