M365 Identity Device Code Grant by an Unusual User (Non-Compliant Device)

Description

Identifies a Microsoft 365 user completing an OAuth device code grant ("Cmsi:Cmsi") from a non-compliant device for the first time within the rule's historical window, regardless of the requesting application or target resource. Device code phishing kits complete the full login (password and MFA) at the genuine Microsoft endpoint and harvest the resulting token by polling, so MFA does not stop them. Because the victim authorizes the flow in their own browser, the grant is frequently completed on a personal or attacker-controlled device that is not enrolled or compliant with the organization's device policies. A user appearing with this device code flow on a non-compliant device for the first time in the lookback window is a strong early indicator of device code phishing, and removing the application and target constraints catches grants against any first-party application, not just the Microsoft Authentication Broker.

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.

Detection requirements

Platform: Containers ESXi IaaS Identity Provider Linux macOS Network Devices Office Suite SaaS Windows
The rule states no platform. This is derived from the 3 ATT&CK techniques it maps to.
Log source category: event_index

Known benign triggers

A user legitimately using the device code flow for the first time on a personal or otherwise non-compliant device, such as a smart TV, kiosk, IoT device, conference room device, or a personal laptop for a CLI or headless developer workflow. Review the source ASN, geolocation, application, and the user's device posture to confirm whether the activity is expected before escalating.

References

Links the source published beside this detection. Reference is the link the source wrote, unmodified. Class is decided by this catalogue from the host and path, not stated by the source. Cited by counts published detections citing the same resource, including this one, and the sources beneath it count the repositories this catalogue ingests, which is not the same as independent research.
Reference	Class	Cited by
arcticwolf.com/resources/blog/kali365-expands-into-aws-microsoft-okta-xerox-max-messenger/	Unclassified	2
arcticwolf.com/resources/blog/token-bingo-dont-let-your-code-be-the-winner/	Unclassified	7
www.ic3.gov/PSA/2026/PSA260521	Unclassified	6
www.microsoft.com/en-us/security/blog/2025/02/13/storm-2372-conducts-device-code-phishing-campaign/	Threat report	4
www.volexity.com/blog/2025/02/13/multiple-russian-threat-actors-targeting-microsoft-device-code-authentication/	Threat report	5

Detection rules

M365 Identity Device Code Grant by an Unusual User (Non-Compliant Device)

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules