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Entra ID Device-Bound PRT from Unusual Device IP

Detects a first-party FOCI tooling client (Azure CLI, PowerShell, VS Code, Graph CLI, Azure AD PowerShell, or Visual Studio) redeeming a device-bound Primary Refresh Token (PRT) for Microsoft Graph,…

Description

Detects a first-party FOCI tooling client (Azure CLI, PowerShell, VS Code, Graph CLI, Azure AD PowerShell, or Visual Studio) redeeming a device-bound Primary Refresh Token (PRT) for Microsoft Graph, SharePoint/OneDrive, or Exchange Online from a source IP that has not been seen with that deviceid. Replay events are limited to compliant or Intune-managed devices. Adversaries who steal a WAM PRT SSO cookie replay it off-box; the token keeps the workstation deviceid, so this pair is new even when Windows Sign-In for that device is outside a correlation window.

Detection logic

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Detection requirements

Platform
ContainersESXiIaaSIdentity ProviderLinuxmacOSNetwork DevicesOffice SuiteSaaSWindows

The rule states no platform. This is derived from the 4 ATT&CK techniques it maps to.

Log source category
event_index

Known benign triggers

  • A user who runs Azure CLI, Azure PowerShell, VS Code, Graph CLI, or Visual Studio from a new egress (VPN, hotel, Cloud Shell, jump host) while WAM still attaches a compliant or managed workstation deviceid will match on first sight of that IP. Exception: add known developer and Cloud Shell ranges after confirming the client ran there.
  • Microsoft Teams, Office, OneDrive SyncEngine, Authentication Broker, Outlook Mobile, Bing, Azure Portal, and Office 365 Management are omitted because first sight of a mobile or M365 egress IP for those clients is routine.
  • Split-tunnel or dual-homed devices can present a new Microsoft 365 egress for tooling clients. Confirm the IP belongs to the enrolled device before treating the event as cookie theft.

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