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M365 Identity OAuth ROPC Grant via Legacy Authentication Client

Identifies a successful login by a user principal through a legacy authenticated client (such as Authenticated SMTP, IMAP, POP, or Exchange ActiveSync) in the Microsoft 365 Unified Audit Log, evidenced by the…

Description

Identifies a successful login by a user principal through a legacy authenticated client (such as Authenticated SMTP, IMAP, POP, or Exchange ActiveSync) in the Microsoft 365 Unified Audit Log, evidenced by the "BAV2ROPC" user agent. Legacy basic-authentication clients are translated by Entra ID into a Resource Owner Password Credentials (ROPC) grant, a single-factor flow that submits the user's password directly and bypasses interactive multi-factor authentication. This is commonly abused during password spraying and account takeover.

Detection logic

Its licence does not clear it for publishing here

Sunturai publishes a detection's own text where the licence it arrived under has been reviewed and permits it, and Elastic License 2.0 has not. The query as its source wrote it, its canonical form and the hash that pins this revision are in the workspace record.

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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
event_index

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