Unlock Hidden M365 Logs: The Unofficial Sentinel Connector Microsoft Didn't Tell You About + Video

Introduction:

For years, Microsoft Sentinel users have faced a critical visibility gap: missing audit logs from key M365 workloads like Copilot, Power BI, and Data Loss Prevention (DLP). An innovative, unofficial solution built on Microsoft’s own codeless connector framework now bridges this gap, offering a streamlined, infrastructure-light path to ingesting the elusive Audit.General and Audit.DLP logs. This project democratizes advanced security monitoring, making comprehensive M365 telemetry accessible beyond just E5 and Defender for Cloud Apps customers.

Learning Objectives:

Understand the critical M365 audit log gaps filled by the unofficial Sentinel connector and its operational scope.
Learn the step-by-step process to deploy the solution, including Entra ID app registration and Data Collection Rule (DCR) configuration.
Master the underlying API call mechanism and data transformation process that powers this codeless ingestion.

You Should Know:

Understanding the M365 Audit Log Gap and Solution Scope
This solution specifically targets two audit streams previously difficult or impossible to ingest natively into a custom Sentinel table: Audit.General and Audit.DLP.

Audit.General is a powerhouse log containing 29 specialized workloads. Crucially, it includes data from modern AI and productivity tools that are not covered by standard connector suites. Audit.DLP provides a consolidated stream for all Data Loss Prevention events across SharePoint, Exchange, and Endpoints. The connector is architected to complement, not replace, your existing setup. It scopes out logs already well-covered by native connectors for SharePoint, Exchange, Teams, Dynamics, Purview, and Entra ID.

Step-by-Step Guide to Scoping Your Needs:

Inventory Existing Logs: Run a KQL query in your Sentinel logs to check your current `OfficeActivity` table coverage.
```
OfficeActivity
| summarize Count=count() by Operation
| sort by Count desc
```
Identify Missing Workloads: Compare your results against the 29 workloads in Audit.General. Key ones often missing include:

`MICROSOFT.COPILOT`

`POWERBI`

`VIVA` (Suite)

`MICROSOFT.SENTINEL` (platform operations)

`EDISCOVERY`

`SECURITYCOMPLIANCECENTER`

Decision Point: If your security or compliance monitoring requires visibility into these uncovered workloads—especially Copilot interactions or internal Power BI report accesses—this solution is for you.

2. Entra ID App Registration: The Authentication Backbone

The connector uses OAuth 2.0 to authenticate with the Office 365 Management API. This requires a dedicated Entra ID application registration with specific, high-privilege API permissions.

Step-by-Step Guide to App Registration:

1. Create the App Registration:

Navigate to Entra ID > App registrations > New registration.

Give it a descriptive name (e.g., `Sentinel-M365-Audit-Connector`).

Select Accounts in this organizational directory only.

Configure API Permissions: This is the most critical step. Add the following application permissions (not delegated):

`Office 365 Management API` -> `ActivityFeed.Read`

`Office 365 Management API` -> `ActivityFeed.ReadDlp`

`Office 365 Management API` -> `ServiceHealth.Read`

Admin consent is required for these permissions.

3. Generate a Client Secret:

Go to Certificates & secrets > Client secrets > New client secret.
Note down the Secret Value and the Secret ID immediately in a secure location—you cannot retrieve the value later.

Collect Credentials: You will need the following for the connector configuration:
Tenant ID: Found on the app registration’s overview page.
Client ID: Also known as the Application ID, found on the overview page.

Client Secret: The value you just saved.

3. Deploying the Solution: A Three-Step Infrastructure Lift

The project is packaged as a single, downloadable solution from the GitHub repository. Its brilliance lies in bundling everything needed—connectors, Data Collection Endpoint (DCE), Data Collection Rule (DCR), and the table schema—into one deployable ARM template.

Step-by-Step Deployment Guide:

1. Download and Prepare:

Clone or download the solution from the GitHub repo: https://github.com/markolauren/sentinel/tree/main/M365AuditGeneralAndDLPSolution`. Locate the main ARM template file (e.g.,azuredeploy.json`).

2. Deploy via Azure Portal (UI):

In the Azure Portal, search for “Deploy a custom template”.
Select Build your own template in the editor and upload the `azuredeploy.json` file.

Fill in the required parameters:

Resource Group: Target for deployment.

Workspace Name & ID: Your Sentinel Log Analytics workspace details.
DCE Name: A name for the new Data Collection Endpoint.
App Credentials: The Tenant ID, Client ID, and Client Secret from Step 2.

Deploy via Azure CLI (Automation): For scripted or repeatable deployments, use the following Bash commands.

Log in to Azure
az login

Set your subscription context
az account set --subscription "Your-Subscription-Name"

Deploy the ARM template to a resource group
az deployment group create \
--resource-group "Your-Sentinel-RG" \
--template-file "./azuredeploy.json" \
--parameters \
workspaceName="Your-LA-Workspace" \
workspaceResourceId="/subscriptions/XXX/resourcegroups/YYY/providers/microsoft.operationalinsights/workspaces/ZZZ" \
endpointName="My-M365-Audit-DCE" \
tenantId="your-tenant-id" \
clientId="your-client-id" \
clientSecret="your-client-secret"

The deployment automatically provisions the `M365AuditGeneral_CL` custom table with its full 304-column schema.

The Connector’s Engine: Two-Phase API Call & Data Transformation
The “codeless” magic happens through a 3,670-line JSON configuration that defines a sophisticated pipeline. It works by polling the Office 365 Management API, which requires a two-stage call process to retrieve actual log data.

Step-by-Step Guide to the API Mechanism:

Phase 1 – Retrieve Content URLs: The connector first calls the main API endpoint to get a list of available audit blobs.
API Endpoint: `https://manage.office.com/api/v1.0/{tenantId}/activity/feed/subscriptions/content`
This returns JSON containing `contentUri` keys, which are short-lived, signed URLs pointing to the actual log data.
Phase 2 – Fetch and Parse Log Blobs: The connector iterates through the list of `contentUri`s and fetches the data from each.
The raw data from each blob is in JSON-L format, containing the detailed audit records.
Data Transformation: A built-in transformation step (defined in the DCR) parses the nested JSON, flattens the structure, and maps the fields directly into the 304 columns of the `M365AuditGeneral_CL` table. This uses the exact native schema from Microsoft’s audit logs.

5. Querying and Utilizing the New Data

Once deployed and running (initial data may take 30-60 minutes to appear), you can start querying the new `M365AuditGeneral_CL` table.

Step-by-Step Guide to Initial Queries and Use:

1. Verify Data Ingestion:

M365AuditGeneral_CL
| take 10
| project TimeGenerated, Workload_s, Operation_s, UserId_s, ClientIP_s

This basic query confirms logs are flowing and shows key fields.

Investigate Copilot Activity: A primary value of this solution is tracking AI tool usage.
```
M365AuditGeneral_CL
| where Workload_s =~ "MICROSOFT.COPILOT"
| summarize EventCount=count() by Operation_s, UserId_s
| sort by EventCount desc
```
This identifies which users are most actively using Copilot and what types of operations they are performing.

Correlate DLP Alerts: Cross-reference DLP events with user context from other tables.

let DlpEvents = M365AuditGeneral_CL
| where Workload_s contains "DLP"
| project TimeGenerated, UserId_s, DlpPolicy_s, Action_s;
let UserLogons = SigninLogs
| project TimeGenerated, UserId, AppDisplayName, IPAddress;
// Join on approximate time and user
DlpEvents
| join kind=inner UserLogons on $left.UserId_s == $right.UserId
| where datetime_diff('minute', TimeGenerated, TimeGenerated1) between (-5 .. 5)
| take 20

This advanced query helps build a richer incident timeline by associating DLP actions with the user’s recent sign-in location and application.

6. Security Hardening and Maintenance

Deploying a connector with high-privilege API permissions requires deliberate security hardening to protect the credentials and access.

Step-by-Step Security Hardening Guide:

Credential Management: Never store the Client Secret in plain text scripts or tickets. Use Azure Key Vault linked to the DCR for production deployments.

PowerShell to Store Secret in Key Vault:

$secret = ConvertTo-SecureString -String "YourClientSecret" -AsPlainText -Force
Set-AzKeyVaultSecret -VaultName "Your-KV-Name" -Name "M365ConnectorSecret" -SecretValue $secret

2. Network Restrictions (Optional but Recommended): Configure the Entra ID app registration to restrict API calls to specific IPs if your Sentinel instance has a static egress IP.
Navigate to Entra ID > App Registrations > Your App > Authentication.
Under Advanced settings, add your Azure region’s egress IPs for Data Collection Rules.
3. Audit the Auditor: Regularly review the app’s own sign-in and audit logs.
Monitor the `AuditLogs` table for events where `ServicePrincipalName` is your connector’s App ID to detect anomalous usage.

What Undercode Say:

Key Takeaway 1: This solution breaks down licensing barriers to advanced telemetry. By leveraging the public Office 365 Management API, it effectively provides “E5-style” audit log visibility to organizations with lower-tier Microsoft licenses, as long as the audit log itself is enabled in the M365 compliance center. This is a significant leveling of the security playing field.
Key Takeaway 2: The project is a masterclass in using Microsoft’s own extensibility frameworks against their limitations. The codeless connector framework (CCF), designed for simplicity, was engineered here to handle a complex, multi-stage API poll-and-transform workflow. This demonstrates that the true limit of “codeless” solutions is often not technology, but imagination and deep understanding of the underlying protocols.

Analysis:

The community’s overwhelmingly positive reaction highlights a persistent pain point in the Microsoft security ecosystem: the fragmentation of log collection. While Microsoft provides powerful tools, the connectors often lag behind the release of new services (like Copilot), creating dangerous visibility gaps. This unofficial connector is a direct, agile response from within the community—even from a Microsoft employee—to fill that gap. It underscores a trend where power users are no longer waiting for official roadmaps but are building and sharing critical tooling themselves. However, it also introduces considerations around long-term support, update cycles, and the shared responsibility model when using community solutions in a production SOC.

Prediction:

This project will catalyze two significant shifts. First, it will force an acceleration of Microsoft’s official connector roadmap, potentially leading to a native, unified M365 Audit connector in Sentinel within the next 12-18 months. Second, and more importantly, it will inspire a wave of similar community-built “bridge” solutions for other API-based services (like Azure DevOps, Defender for IoT logs, or third-party SaaS platforms), proving the codeless connector framework as a potent platform for security automation beyond its out-of-the-box use cases. The era of the community security engineer as a vital extension of the vendor’s development team has firmly arrived.

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