Microsoft Purview DLP | Lifecycle: Understanding, Evaluating and Automating Signals

DLP Incident Lifecycle

Anyone who activates DLP policies but ignores the alerts is engaging in compliance theater. A DLP system is not a static shield, but a sensor network that requires permanent calibration. When sensitive data leaves the tenant, the quality of your triage processes determines the damage, not just the block action.

The architecture of Microsoft Purview scans data asynchronously; your job is to translate these signals into actionable intelligence before your tea/SOC drowns in false positives.

Triage & Initial Assessment

Your entry point is the Microsoft Defender Portal. This is where the signals come together. Your goal at this stage is to quickly reduce the noise-to-signal ratio. A DLP alert alone says little – only the metadata makes it assessable.

Use the filter logic to separate attacks from accidents. A user who accidentally shares a credit card number is fundamentally different from an account that pulls 50 documents with the label “Strictly Confidential” onto a private USB stick in 10 minutes.

Pay special attention to user justification. If you’ve configured policies with Notify & Allow Override, users will need to justify why they’re bypassing the block. This reasoning is often the fastest indicator of false positives or process gaps.

Simulation & Policy Tuning

Before you activate a DLP rule (“Turn it on”), it must be in simulation mode. The decisive architectural advantage: You test the effect, not just the syntax. In this mode (“Run the policy in simulation mode”), signals are generated, but no block actions are executed and, crucially, your regular incident queue is not flooded.

You don’t analyze the results of this test phase in the global alert queue, but in a dedicated view that is directly attached to the policy. This keeps your operations clean while you tighten the rules in the background.

The workflow for analysis: You’ll navigate to the overview of your DLP policies. As soon as you select a policy that runs in simulation mode, the context bar changes. Here you use the button “View simulation”. This opens an isolated dashboard just for that specific rule.

In this simulation view, you’ll see the following aggregated:

1. Hit rate: How many times would the rule have fired?
2. Matching Items: What specific files or emails were detected?
3. Locations: Where is the data (SharePoint, Exchange, OneDrive)?

Use this view to test the match rate against reality. Does your new rule for “internal project code” fire on every email signature? Here you can see the pattern immediately. Only when the false positive rate in this view is below your defined threshold (e.g < . 5%) do you leave the simulation and activate the rule.

Microsoft Defender XDR

Once your rule is “sharp” and kicks in, we leave the configuration level. Your first port of call for incoming signals is no longer the Purview Portal, but the Microsoft Defender Portal.

This is where DLP alerts converge with EDR (Endpoint) and Identity alerts. Why is this important for you as an architect? Because DLP incidents rarely happen in isolation.

A) The Incident Queue (Single Pane of Glass) DLP alerts end up in the same queue as malware detections. This allows your SOC team to see connections: Did the user perhaps open a phishing email before uploading the sensitive data? In the Defender Portal, an isolated “DLP rule hit” becomes a context-rich “incident story”.

B) The Alert Story & Correlation When you click on a DLP incident, you don’t just see “File X blocked”. You can see the attack story.

• Assets: Which laptop? Which user?
• Graph: How does this DLP breach relate to other security events?
• Management: Here you assign the incident to an analyst, set tags or classify it (True/False Positive), which in turn can be read out via API (see Section 6).

When will you change the portal? Defender is perfect for managing the incident (status, assignment, context). But if you want to know what exactly was in the file (content preview) or what specific metadata changes happened, jump into Purview Explorer (see next section).

DLP | The Forensics Suite

An alert only provides you with the trigger (time and trigger), but rarely the context. To evaluate an incident and rule out false positives, you need to answer two questions: “What exactly does it say?” (Content) and “What happened before/after?” (correlation).

Before you use the tools, you have to do a check . Without it, you run into technical errors (“Access Denied”) or logical misconceptions.

Check: Latency, License & Roles

1. Latency (Warning) | If auditing or compliance features have only been active for <24 hours , the explorers do not provide reliable data.

• The reason: Backend indexing to the Unified Audit Log is asynchronously delayed.
• The consequence: An empty view at this stage is not evidence of inactivity (false negative), but merely a pipeline lag. Never close tickets based on this temporary blindness.

2. License Wall (E5 required!) | When you try to dive deep into the data (“Eyes on Data”), you will encounter a hard technical barrier. The tenant strictly checks your licensing before decrypting the content in the viewer, there is no gray area (“grace period”) here.

• Learn about the features in each license | MS365 | Service Guide

3. RBAC Lock (The Two-Stage Model) | Even as a Global Admin, you’re restricted here by default. Microsoft makes a strict distinction in the Purview portal between “know where it is” (list) and “know what’s in it” (content).

When you select a data source, an error message comes up, most of the time you lack the second permission level. You must be a member of the following role groups :

• Path: Purview Portal > Einstellungen > Rollen und Bereiche > Rollengruppen.
  
• The required roles: Look for the correct roles, which are:
  • 🇺🇸 Content Explorer Content Viewer
  • 🇺🇸 Content Explorer List Viewer

Replication: After assignment, allow up to 60 minutes of waiting time for the role group to update.

A) Data Explorer / Overview

This is your entry point (usually “Overview” in the menu). You check the flight altitude here to estimate the extent (isolated incident vs. systemic problem).

The Teaser Trap (License Check): The dashboard itself is often visible (“Free Teaser”). You’ll see data sources with things like “150 credit card numbers.” But be careful: As soon as you click on a data source to see which SharePoint site is affected (drill-down), the license lock takes effect!

• Without E5/Add-On: You will immediately receive the blocker: “Update your subscription… To access and use Content Explorer, your organization must have […] Microsoft 365 E5 Compliance Add-on.”
• With E5/Add-On: You will seamlessly jump to the list view of the affected files.

B) Content Explorer (proof)

Here you zoom from the big to the small. To validate the risk, you need to see the content (“Eyes on Data”).

Attention | The Dead End (Level 1): If you didn’t follow the pre-check (see above: Level 2 role), your journey ends here! You’ll see the stats (aggregation: “This location contains 3 credit card numbers”), but you’ll be technically blocked when you try to open the location. You get stuck on the stats level.

Level 2 and further down (the drill-down): If the roles fit, you can select the respective locations and see the corresponding files.

• The proof: The system renders the plain text of the file in the respective location in the preview window.
• The validation: Here you actually verify: Is the recognized “credit card number” really sensitive, or is it just an internal order number that happens to pass the Luhn algorithm check (false positive)?

⚠️ Note – Works Council & Data Protection | Access to Content Explorer leaves an indelible trace. When you open a file, it’s logged in the admin audit log. Rule: Only access content if there is a reasonable suspicion and the incident process legitimizes it. In many organizations, the works council, the data protection officer (DPO) or the information security officer (ISB) must be consulted for this purpose (four-eyes principle).

C) Activity Explorer (context)

After verifying the content (B), check the historical causal chain here to evaluate the user’s intent . A simple “share” process can be harmless. But the Activity Explorer aggregates the metadata timeline around the event:

• Obfuscation: Did the user rename the file en masse shortly before?
• Downgrade: Has a sensitivity label been removed?
• Exfiltration: Was the content copied to a USB stick or to a private cloud?

User Education & Reporting

DLP isn’t just technology, it’s psychology. Your architecture needs to serve two audiences: the end user (so they change their behavior) and management (so they understand the risk status).

A) The “Human Firewall”

Policy Tips & Warnings The most effective alert is the one you never see as an admin because the user has solved it himself. Policy tips are your first line of defense. They appear directly in the workflow (Outlook, Teams, Word) before the user presses “Send”.

• Architect-Rule: Don’t configure policy tips with generic texts (“Blocked because of DLP”). Use custom texts: “This file contains credit card information. Please remove them or use the ‘Confidential’ label to send encrypted.” This drastically reduces tickets in the help desk.
  
• Incident Reports (E-Mail): For admins, don’t let yourself be spammed. Enable email reports in the policy only for high-severity incidents or mass violations (volume threshold), otherwise the alerts will end up in your Outlook rule “Delete Read”.

B) Status Reports

“Trust is good, control is architecture.” You used to laboriously correlate CSV exports. Today you use the Posture Reports (preview) in the Purview Portal. This view shifts the focus from pure statistics (“100 hits”) to effectiveness (“Is the rule working correctly?”).

You can find them under DLP > Reports > Posture Reports. Use it for three specific architecture checks:

1. Rule Events (The Fine-Tuning) Here you can see the most frequently triggered individual rules (not just the whole policy) and the resulting actions (block, override, info).

• Architect’s View: If a rule generates 90% of the “overrides”, it is technically correct (it matches), but procedurally incorrect (it interferes).
• Action: This is your indicator to add exceptions or adjust the confidence level.

2. Policy Events (The Scope Check) This report zooms out and shows the activity across all workloads (Exchange, Teams, Endpoint).

• Architect’s View: Do you see a total silence on “Teams” here, even though the policy should be active? This often indicates scope errors (false inclusion/exclusion of groups).
• Action: Validate here whether the distribution of hits meets your expectations (e.g. 80% Endpoint, 20% Exchange).

3. User Risk (The “Repeat Offenders”) DLP is often a training problem. This report identifies users who are repeatedly violating policies across workloads.

• Architect’s View: A user who ignores 50 warnings a day does not need IT adaptation, but a conversation with the supervisor or training. Technical rules cannot fix human behavior.

C) Diagnostics (troubleshooting)

When a DLP rule doesn’t work, the big guessing often begins: Is it latency? At the RegEx? On the scope? Microsoft has integrated hidden but powerful diagnostic widgets directly into the portal for this purpose. Instead of waiting hours for logs, you start a targeted check here.

Under Diagnostics , select the appropriate scenario:

Tip: Before you open a support ticket with Microsoft, be sure to run the appropriate diagnostics. The result will often give you a “RunId” or a specific error code that cuts the resolution time in half.

Graph API | Classify & Report

Microsoft has recently delivered an important architecture component with an update (to the news): The explicit classification of DLP alerts. Administrators can now assign a status of True Positive, False Positive , or Benign Positive to alerts. This metadata is synchronized bi-directionally with the Microsoft Defender portal.

The UI is acceptable for individual analysis, but inefficient for scalable security operations (SecOps). To make DLP data truly usable, for example for automated reports or feeding SIEM systems, we need to address the data layer directly. The solution is the alerts_v2 endpoint of the Microsoft Graph API.

An alert without context is worthless. By writing back the classification (“triage”), we close the control loop:

• Policy Tuning: If 90% of a rule’s alerts are marked as “false positives,” the rule is broken, not user behavior.
  
• Incident Response: A “true positive” triggers escalation processes, while “benign positives” (e.g., approved tests) are documented for compliance audits.

Prerequisites and scope

We use the Microsoft Graph PowerShell SDK because it abstracts authentication and token handling.

For write access to alerts, the permission scope SecurityAlert.ReadWrite.All is mandatory. A pure one Read.All is sufficient for reporting, but fails in the update attempt.

# Verbindung mit dem notwendigen Scope herstellen
Connect-MgGraph -Scopes "SecurityAlert.ReadWrite.All" -NoWelcome

Note: The scope ‘SecurityAlert.ReadWrite.All’ requires one-time approval from a Global Admin (Admin Consent).

Step 1: Targeted retrieval alerts_v2

The Graph Security API aggregates signals from various sources (Defender for Endpoint, Identity, Cloud Apps). To get only DLP-relevant data, we filter server-side for the serviceSource. This significantly reduces payload and latency.

We use Get-MgSecurityAlertV2, the direct interface to the modern alerts_v2 endpoint.

# Abruf der DLP-Alerts (Letzte 500, sortiert nach Erstellungsdatum)
[array]$DLPAlerts = Get-MgSecurityAlertV2 `
    -Filter "serviceSource eq 'dataLossPrevention'" `
    -PageSize 500 `
    -All `
    -Sort "CreatedDateTime Desc"

# Validierung der Rohdaten
$DLPAlerts | Select-Object -First 1 Id, Title, Classification, Status

Step 2: Classify alerts

Manual tagging in the Purview Portal is time-consuming. We can make mass changes via PowerShell – for example, set all alerts of a certain time window or title as “In Progress”.

This is where the following is Update-MgSecurityAlertV2 used. We update not only the classification, but also the processing status (status) and the assignment (assignedTo) to clearly map the “chain of custody”.

Important: The API expects specific enum values for classification (truePositive, , falsePositive, unknowninformationalExpectedActivity, ).

# Beispiel: Einen spezifischen Alert greifen und klassifizieren
$TargetAlertId = $DLPAlerts[0].Id 

# Definition der Update-Parameter
$UpdateParams = @{
    determination  = "other"           # Grund der Entscheidung
    status         = "inProgress"      # Workflow-Status
    assignedTo     = "secops@contoso.com" 
    classification = "truePositive"    # Die eigentliche Bewertung
}

# Update durchführen
Update-MgSecurityAlertV2 -AlertId $TargetAlertId -BodyParameter $UpdateParams

This call immediately sets the status in the backend and is visible in both the Purview Portal and Microsoft Defender shortly afterwards.

Step 3: Management Reports

The raw API responses are deeply nested JSON objects. For management summaries or CSV exports, we need to “flatten” the data. We extract only the operationally relevant fields into a PSCustomObject.

This script produces a clean list that can be exported immediately or parsed in a GridView:

$Report = [System.Collections.Generic.List[Object]]::new()

ForEach ($Alert in $DLPAlerts) {
    # Zeitstempel normalisieren
    $LastUpdated = If ($Alert.LastUpdateDateTime) { 
        Get-Date $Alert.LastUpdateDateTime -Format 'dd.MM.yyyy HH:mm' 
    } Else { 
        "N/A" 
    }

    # Custom Object für saubere Tabellenstruktur
    $ReportLine = [PSCustomObject][Ordered]@{
        Id             = $Alert.Id
        Title          = $Alert.Title
        Created        = Get-Date $Alert.CreatedDateTime -Format 'dd.MM.yyyy HH:mm'
        Severity       = $Alert.Severity
        Status         = $Alert.Status
        Category       = $Alert.Category
        AssignedTo     = $Alert.AssignedTo
        Updated        = $LastUpdated
        Classification = $Alert.Classification # Das neue Feld
    }
    $Report.Add($ReportLine)
}

# Ausgabe zur Analyse
$Report | Out-GridView -Title "DLP Alert Classification Report"
# Optional: Export
# $Report | Export-Csv -Path "C:\Temp\DLP_Report.csv" -NoTypeInformation -Encoding UTF8

Conclusion: From noise to strategy

An isolated DLP alert is technically worthless – only the context makes it actionable. True control comes when you break down the silos between compliance (Purview) and security (Defender/Sentinel) and don’t just see the new classification options as a UI update.

Use the API (Update-MgSecurityAlertV2) not only to consume alerts, but to actively enrich them with context. This process must be circular: The historical database obtained in this way provides you with the metrics to precisely refine your “Sensitive Information Types” (SITs) and confidence levels. Automating this feedback loop transforms DLP from a reactive “click” to proactive incident management that reliably separates real risks from background noise.

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