[New Rule] Microsoft Entra ID SharePoint Access for User Principal via Auth Broker

[terrancedejesus]

Pull Request

Issue link(s):

• https://github.com/elastic/ia-trade-team/issues/590

Summary - What I changed

Adding detection coverage for https://github.com/elastic/ia-trade-team/issues/590.

This rule detects non-interactive authentication activity against SharePoint Online (Office 365 SharePoint Online) by
a user principal via the Microsoft Authentication Broker application. The session leverages a refresh token or Primary
Refresh Token (PRT) without interactive sign-in, often used in OAuth phishing or token replay scenarios.

• Focuses on MSFT Entra Sign In Logs
• Inclusion for the source app ID being first-party MSFT auth broker: 29d9ed98-a469-4536-ade2-f981bc1d605e
• Inclusion for target resource ID being first-party MSFT sharepoint online: 00000003-0000-0ff1-ce00-000000000000
• Ensures identity and user principal names are not null --> indicating user principal and not service principals
• Inclusion for Entra ID OAuth refresh tokens or primary refresh tokens. Note that in order to obtain a PRT, a refresh token must be obtained via prior OAuth phishing, then device registration
• Inclusion for auth interactive being false to key in on programmatic use like via HKTLs

How To Test

• Please refer to the meta regarding testing for this behavior
• TRADE's serverless stack can be used to run query and review hits from emulation

Checklist

• Added a label for the type of pr: bug, enhancement, schema, maintenance, Rule: New, Rule: Deprecation, Rule: Tuning, Hunt: New, or Hunt: Tuning so guidelines can be generated
• Added the meta:rapid-merge label if planning to merge within 24 hours
• Secret and sensitive material has been managed correctly
• Automated testing was updated or added to match the most common scenarios
• Documentation and comments were added for features that require explanation

Contributor checklist

• Have you signed the contributor license agreement?
• Have you followed the contributor guidelines?

[github-actions]

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