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Entra ID OAuth Authorization Code Grant for Unusual User, App, and Resource

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Entra ID OAuth Authorization Code Grant for Unusual User, App, and Resource

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Identifies the first occurrence of an OAuth 2.0 authorization code grant flow for a specific combination of client application, target resource, and user principal in Microsoft Entra ID. Developer tools like Azure CLI, Visual Studio Code, and Azure PowerShell accessing Microsoft Graph or legacy Azure AD are flagged for infrequent or first time usage by a user. Additionally, any FOCI (Family of Client IDs) application accessing the deprecated Windows Azure Active Directory for the first time is flagged since this resource is rarely accessed legitimately. This pattern is indicative of OAuth phishing attacks like ConsentFix, where attackers steal authorization codes and exchange them for tokens from attacker controlled infrastructure.

Rule type: new_terms

Rule indices:

  • filebeat-*
  • logs-azure.signinlogs-*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Domain: Cloud
  • Domain: Identity
  • Data Source: Azure
  • Data Source: Microsoft Entra ID
  • Data Source: Microsoft Entra ID Sign-in Logs
  • Use Case: Identity and Access Audit
  • Use Case: Threat Detection
  • Tactic: Initial Access
  • Tactic: Credential Access
  • Resources: Investigation Guide

Version: 1

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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Triage and analysis

Investigating Entra ID OAuth Authorization Code Grant for Unusual User, App, and Resource

This New Terms rule detects the first occurrence of an OAuth 2.0 authorization code grant flow for a specific combination of client application ID, target resource ID, and user principal within the last 14 days. When a user has never used a particular app+resource combination and it involves FOCI applications or legacy Azure AD, this may indicate OAuth phishing attacks like ConsentFix.

The rule is particularly effective at catching attacks where adversaries use stolen OAuth codes with first-party apps to access resources the victim has never accessed before. For example, if a non-developer suddenly uses Azure CLI to access legacy AAD for the first time, this is highly suspicious regardless of other factors.

Possible investigation steps

  • Review azure.signinlogs.properties.user_principal_name to identify the affected user and determine if they are a developer who would legitimately use these tools.
  • Check azure.signinlogs.properties.app_display_name to confirm which application was used. Azure CLI or PowerShell access by non-technical users is suspicious.
  • Examine azure.signinlogs.properties.resource_id to identify the target resource. Legacy AAD (00000002-0000-0000-c000-000000000000) access is unusual for most users.
  • Analyze source.ip and source.geo.* for geographic anomalies. ConsentFix attackers exchange codes from different IPs than the victim.
  • Review azure.signinlogs.properties.is_interactive - if this is a non-interactive sign-in shortly after an interactive one from a different IP, it indicates token replay.
  • Correlate with other sign-in events using azure.signinlogs.properties.session_id to identify the full OAuth flow sequence.
  • Pivot to azure.graphactivitylogs to search for subsequent Graph API or AAD API activity from unusual locations.
  • Check azure.auditlogs for device registration events around the same timeframe.

False positive analysis

  • Developers or IT administrators legitimately using Azure CLI, PowerShell, or VS Code for the first time to access specific resources.
  • Users onboarding to new development environments or receiving new tooling.
  • Automation scripts that run with user-delegated permissions for the first time.
  • Consider the user’s role and typical activity patterns when evaluating alerts.

Response and remediation

  • Contact the user to confirm if they initiated the OAuth flow and used the detected application.
  • If unauthorized, immediately revoke all refresh tokens for the user via Microsoft Entra ID.
  • Review recent activity from the same session_id for signs of data access or enumeration.
  • Block the source IP if confirmed malicious.
  • Implement Conditional Access policies to restrict OAuth flows for these applications to compliant devices.
  • Educate users about OAuth phishing and the risks of pasting authorization codes.

Rule query

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event.dataset: "azure.signinlogs" and
    event.outcome: "success" and
    azure.signinlogs.properties.user_type: "Member" and
    (
        (
            azure.signinlogs.properties.app_id: (
                "04b07795-8ddb-461a-bbee-02f9e1bf7b46" or
                "aebc6443-996d-45c2-90f0-388ff96faa56" or
                "1950a258-227b-4e31-a9cf-717495945fc2"
            ) and
            azure.signinlogs.properties.resource_id: (
                "00000002-0000-0000-c000-000000000000" or
                "00000003-0000-0000-c000-000000000000"
            )
        ) or
        (
            azure.signinlogs.properties.app_id: (
                "00b41c95-dab0-4487-9791-b9d2c32c80f2" or
                "1fec8e78-bce4-4aaf-ab1b-5451cc387264" or
                "26a7ee05-5602-4d76-a7ba-eae8b7b67941" or
                "27922004-5251-4030-b22d-91ecd9a37ea4" or
                "4813382a-8fa7-425e-ab75-3b753aab3abb" or
                "ab9b8c07-8f02-4f72-87fa-80105867a763" or
                "d3590ed6-52b3-4102-aeff-aad2292ab01c" or
                "872cd9fa-d31f-45e0-9eab-6e460a02d1f1" or
                "af124e86-4e96-495a-b70a-90f90ab96707" or
                "2d7f3606-b07d-41d1-b9d2-0d0c9296a6e8" or
                "844cca35-0656-46ce-b636-13f48b0eecbd" or
                "87749df4-7ccf-48f8-aa87-704bad0e0e16" or
                "cf36b471-5b44-428c-9ce7-313bf84528de" or
                "0ec893e0-5785-4de6-99da-4ed124e5296c" or
                "22098786-6e16-43cc-a27d-191a01a1e3b5" or
                "4e291c71-d680-4d0e-9640-0a3358e31177" or
                "57336123-6e14-4acc-8dcf-287b6088aa28" or
                "57fcbcfa-7cee-4eb1-8b25-12d2030b4ee0" or
                "66375f6b-983f-4c2c-9701-d680650f588f" or
                "9ba1a5c7-f17a-4de9-a1f1-6178c8d51223" or
                "a40d7d7d-59aa-447e-a655-679a4107e548" or
                "a569458c-7f2b-45cb-bab9-b7dee514d112" or
                "b26aadf8-566f-4478-926f-589f601d9c74" or
                "c0d2a505-13b8-4ae0-aa9e-cddd5eab0b12" or
                "d326c1ce-6cc6-4de2-bebc-4591e5e13ef0" or
                "e9c51622-460d-4d3d-952d-966a5b1da34c" or
                "eb539595-3fe1-474e-9c1d-feb3625d1be5" or
                "ecd6b820-32c2-49b6-98a6-444530e5a77a" or
                "f05ff7c9-f75a-4acd-a3b5-f4b6a870245d" or
                "f44b1140-bc5e-48c6-8dc0-5cf5a53c0e34" or
                "be1918be-3fe3-4be9-b32b-b542fc27f02e" or
                "cab96880-db5b-4e15-90a7-f3f1d62ffe39" or
                "d7b530a4-7680-4c23-a8bf-c52c121d2e87" or
                "dd47d17a-3194-4d86-bfd5-c6ae6f5651e3" or
                "e9b154d0-7658-433b-bb25-6b8e0a8a7c59"
            ) and
            azure.signinlogs.properties.resource_id: "00000002-0000-0000-c000-000000000000"
        )
    )

Framework: MITRE ATT&CKTM

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