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MediumSplunk security contentSteven Dick

O365 Multiple OS Vendors Authenticating From User

The following analytic identifies when multiple operating systems are used to authenticate to Azure/EntraID/Office 365 by the same user account over a short period of time. This activity could be indicative of…

Description

The following analytic identifies when multiple operating systems are used to authenticate to Azure/EntraID/Office 365 by the same user account over a short period of time. This activity could be indicative of attackers enumerating various logon capabilities of Azure/EntraID/Office 365 and attempting to discover weaknesses in the organizational MFA or conditional access configurations. Usage of the tools like "MFASweep" will trigger this detection.

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.

Log source category
office_365_universal_audit_log

Known benign triggers

  • IP or users where the usage of multiple Operating systems is expected, filter accordingly.

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