493291 – Microsoft Purview compliance portal: Data Loss Prevention – Detection of True file type in EXO DLP

Product:

Exchange, Purview Communication Compliance, Purview Data Loss Prevention

Platform:

US Instances, Web, World tenant

Status:

In development

Change type:

Links:

Details:

Traditionally, Exchange has relied solely on the file extension (e.g., .docx, .pdf) to identify the type of an attachment. However, this approach can be bypassed if a file is renamed with a misleading extension. To address this, we’re enhancing our detection logic to go beyond just the visible file extension. With this update, even if a file’s extension is altered, Exchange will evaluate the actual content of the file to determine its true type. This ensures that policies based on file type—such as “File extension is…”—remain effective and secure, even in cases of renamed or disguised attachments. This improvement provides customers with a more robust and reliable way to enforce compliance and security rules around file sharing.

Change Category:
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Scope:
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Release Phase:
General Availability, Preview

Created:
2025-05-10

updated:
2025-05-10

Public Preview Start Date

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Docu to Check

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MS workload name

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summary for non-techies**

Microsoft is enhancing Exchange to analyze file content rather than just relying on file extensions, improving security by accurately identifying file types even if extensions are altered.

Direct effects for Operations**

File Type Detection Enhancement
The change may lead to temporary disruptions in file sharing processes as users adapt to the new detection logic, potentially causing confusion and delays in communication.
   - roles: Compliance Officer, IT Support Specialist
   - references: https://techcommunity.microsoft.com/t5/security-compliance-identity/microsoft-purview-compliance-portal-data-loss-prevention-detection/ba-p/3741230

Policy Enforcement Reliability
If the change is implemented without proper preparation, there may be a risk of false positives or negatives in file type detection, leading to unintended blocking of legitimate files or allowing harmful files to pass through.
   - roles: Compliance Officer, Data Protection Officer
   - references: https://techcommunity.microsoft.com/t5/security-compliance-identity/microsoft-purview-compliance-portal-data-loss-prevention-detection/ba-p/3741230

Configutation Options**

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Data Protection**

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IT Security**

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explanation for non-techies**

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