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Introduction:
Microsoft Sentinel’s native connectors often miss critical Microsoft 365 audit events, especially Data Loss Prevention (DLP) logs and granular workload-specific audit trails from 29 specialty services. A newly merged community solution built with Sentinel’s Codeless Connector Framework (CCF) now bridges this gap by ingesting the complete Unified Audit Log into a single custom table, eliminating the need for Defender for Cloud Apps to access these high-fidelity events.
Learning Objectives:
- Deploy the Audit.General and Audit.DLP connectors from Sentinel GitHub using CCF to ingest 30 workload schemas into the `M365AuditGeneral_CL` table.
- Query 321 columns of unified audit data for threat hunting, DLP incident response, and compliance monitoring.
- Automate O365 Management Activity API authentication and troubleshoot ingestion failures with PowerShell and KQL.
You Should Know:
- Deploying the Custom CCF Connector via Azure Sentinel GitHub
The connector consists of two independent data sources: Audit.General (29 workloads, including Exchange, SharePoint, Teams, Power BI, and Purview) and Audit.DLP (dedicated DLP rule matches and false-positive events). Unlike the native M365 connector, this custom solution uses the exact same schema as the Unified Audit log, stored in `M365AuditGeneral_CL` with 321 columns.
Step‑by‑step deployment:
- Prerequisites: Global Admin or Security Admin role in Azure, and access to the O365 Management Activity API (enabled by default for most tenants).
- Clone or download the Sentinel GitHub repository:
git clone https://github.com/Azure/Azure-Sentinel.git
- Navigate to the `Solutions/Microsoft 365 Audit General & DLP/` folder.
- In Azure Portal → Microsoft Sentinel → Content hub → “Create custom connector” → Upload the provided ARM template.
- Configure API authentication: register an App Registration in Azure AD with the `ActivityFeed.Read` and `ActivityFeed.ReadDlp` permissions (delegated), and grant admin consent.
- Deploy the connector using the PowerShell script `Deploy-CCFConnector.ps1` from the repo:
.\Deploy-CCFConnector.ps1 -SubscriptionId "<your-sub-id>" -ResourceGroup "<sentinel-rg>" -WorkspaceName "<workspace>" -TenantId "<tenant-id>" -ClientId "<app-id>" -ClientSecret "<secret>"
- After deployment, data will start flowing into the custom table within 15 minutes. Verify with KQL:
M365AuditGeneral_CL | take 10 | project TimeGenerated, Operation_CL, Workload_CL, UserId_s
2. Querying DLP Events for Insider Risk Investigation
DLP events from the `Audit.DLP` connector populate the same table with a `Workload_CL = “DLP”` and contain fields like RuleName_s, SensitiveInfoType_s, `Action_s` (e.g., “Blocked”, “Allowed”), and File_Name_s. This allows you to correlate DLP alerts with general audit activities (e.g., a user exfiltrating data after a DLP rule match).
Step‑by‑step hunting query:
- Find all DLP blocks on SharePoint within the last 24 hours:
M365AuditGeneral_CL | where TimeGenerated > ago(24h) | where Workload_CL == "DLP" | where Action_s contains "Blocked" | where Operation_CL contains "SharePoint" | project TimeGenerated, UserId_s, RuleName_s, File_Name_s, SensitiveInfoType_s, Action_s
- To identify users who triggered DLP and then performed suspicious logins:
let DlpUsers = M365AuditGeneral_CL | where Workload_CL == "DLP" and Action_s == "Blocked" | summarize by UserId_s; M365AuditGeneral_CL | where UserId_s in (DlpUsers) | where Operation_CL == "UserLoggedIn" and ResultStatus_s != "Success" | project TimeGenerated, UserId_s, ClientIP_s, ResultStatus_s
- Windows/Linux command to monitor real-time ingestion: Use Azure CLI to check connector status.
az sentinel data-connector list --workspace-1ame <workspace> --resource-group <rg> --query "[?contains(name,'M365Audit')].{Name:name, State:state}"
3. Automating Failover and API Rate‑Limit Handling
The O365 Management Activity API has a throttling limit of 5,000 requests per 10 minutes. The CCF connector automatically handles retries and backoff, but you can monitor throttling events in the `SentinelHealth_CL` table.
Step‑by‑step resilience setup:
- Create an Azure Automation runbook that checks for ingestion gaps by comparing the last ingested timestamp from `M365AuditGeneral_CL` against the current UTC time.
- If a gap > 1 hour is detected, restart the connector via PowerShell:
$connector = Get-AzSentinelDataConnector -ResourceGroupName "<rg>" -WorkspaceName "<workspace>" | Where-Object {$_.Name -like "M365Audit"} Disable-AzSentinelDataConnector -ResourceId $connector.Id Start-Sleep -Seconds 30 Enable-AzSentinelDataConnector -ResourceId $connector.Id - For Linux-based monitoring (e.g., using Azure Functions), parse the health table with curl and jq:
az monitor query -w <workspace> -rg <rg> --analytics-query "SentinelHealth_CL | where DataConnectorType_s == 'M365AuditGeneral' | top 1 by TimeGenerated desc | project IngestionLatency_s" -o tsv
4. Hardening API Security and Least‑Privilege Access
The client secret used for OAuth authentication is stored in Sentinel’s connector configuration. To prevent compromise:
– Rotate the secret every 90 days using Azure Key Vault and update the connector via the CCF API.
– Restrict the App Registration’s IP whitelist to Azure Sentinel’s outbound IPs only.
– Use Managed Identity instead of client secret when running from an Azure VM or Function App.
Step‑by‑step migration to Managed Identity:
- Enable system-assigned managed identity on your Sentinel Logic App or Automation Account.
- Grant that identity the `ActivityFeed.Read` and `ActivityFeed.ReadDlp` API permissions in Azure AD.
- Modify the CCF connector’s ARM template to replace `clientSecret` with
"useManagedIdentity": true. - Redeploy the connector. No secrets are stored in plaintext.
5. Enriching Detections with Custom Analytics Rules
Because the unified table contains 321 columns, you can build analytics rules that previously required multiple tables or expensive joins. Example: Detect bulk deletion of emails followed by a DLP override.
Step‑by‑step rule creation:
- In Sentinel → Analytics → Create scheduled rule.
- Rule query:
let BulkDeletes = M365AuditGeneral_CL | where Workload_CL == "Exchange" | where Operation_CL has "SoftDelete" or Operation_CL has "HardDelete" | summarize DeletedCount = count() by UserId_s, bin(TimeGenerated, 5m); BulkDeletes | where DeletedCount > 50 | join kind=inner ( M365AuditGeneral_CL | where Workload_CL == "DLP" and Action_s == "Override" | project DLPTime=TimeGenerated, UserId_s, RuleName_s, OverrideReason_s ) on UserId_s | where DLPTime between (TimeGenerated .. TimeGenerated+10m)
- Set frequency to 5 minutes, incident creation threshold >0. Add entity mapping for `UserId_s` to Account.
What Undercode Say:
- Key Takeaway 1: The native M365 connector misses DLP events and many workload-specific audit logs; this CCF solution closes a massive detection gap without requiring expensive Defender for Cloud Apps licenses.
- Key Takeaway 2: Using a single custom table with 321 columns standardizes hunting across Exchange, Teams, DLP, and 27 other workloads, drastically reducing query complexity and join performance issues.
Analysis (approx. 10 lines):
By ingesting the complete Unified Audit log into Sentinel, security teams gain visibility into data theft attempts (DLP blocks), policy violations, and administrator actions across 30 workloads. The CCF approach is codeless, meaning no maintenance of custom API polling scripts. However, organizations must ensure proper RBAC on the `M365AuditGeneral_CL` table, as it contains highly sensitive audit data including user identities and file paths. The 321-column schema may initially overwhelm analysts, but targeted KQL queries using `project` and `where` filters mitigate this. This solution also enables near-real-time correlation with other Sentinel data sources (e.g., Defender for Endpoint alerts) because all events land in a single workspace. The GitHub merge signals Microsoft’s validation, but note that the connector relies on the O365 Management Activity API’s eventual consistency – logs may take 5–15 minutes to appear. For SOCs with compliance mandates (e.g., FINRA, HIPAA), this fills a critical logging gap that previously required third‑party tools.
Prediction:
- -1 Licensing friction: Microsoft may eventually restrict O365 Management Activity API access for non‑E5 tenants, forcing organizations to upgrade or risk losing this free enrichment.
- +1 Community fork potential: Because this connector is open source, expect rapid community contributions adding support for additional workloads (e.g., Power Automate, Viva Insights) beyond the 29 currently included.
- +1 Cross‑platform hunting standardization: The unified schema will likely influence Microsoft to redesign the native M365 connector, simplifying threat hunting for all Sentinel users by 2027.
- -1 Data ingestion costs: 321 columns per event can dramatically increase log volume – implement column-level filtering in the CCF configuration to exclude unused fields if cost becomes prohibitive.
- +1 Automated DLP incident response: With low-latency DLP events, teams can build Logic Apps that automatically quarantine files, revoke user sessions, or isolate devices when a high‑severity DLP rule matches.
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