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

Vendor: Microsoft
Product: Microsoft 365
Type: Security
Announcement date: 2025-05-09
Effective date: Date not published
Impact: Affected

In brief

What the source says

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. GA date: August CY2025 Preview date: July CY2025 Launched General Availability Preview Worldwide (Standard Multi-Tenant) GCC GCC High Microsoft 365 Microsoft Purview Web

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Who is affected: The audience described by the Microsoft update is represented by: Microsoft Purview compliance portal: Data Loss Prevention - Detection of True file type in EXO DLP 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

Why it matters: The change matters because the official source describes: Microsoft Purview compliance portal: Data Loss Prevention - Detection of True file type in EXO DLP 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

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Raw capture
2026-08-29T09:22:49.319599+00:00
Event
Microsoft Purview compliance portal: Data Loss Prevention - Detection of True file type in EXO DLP 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. GA date: August CY2025 Preview date: July CY2025 Launched General Availability Preview Worldwide (Standard Multi-Tenant) GCC GCC High Microsoft 365 Microsoft Purview Web
source
Product Microsoft 365
Microsoft Purview compliance portal: Data Loss Prevention - Detection of True file type in EXO DLP 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. GA date: August CY2025 Preview date: July CY2025 Launched General Availability Preview Worldwide (Standard Multi-Tenant) GCC GCC High Microsoft 365 Microsoft Purview Web
source
Insight a salesperson
Microsoft Purview compliance portal: Data Loss Prevention - Detection of True file type in EXO DLP 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. GA date: August CY2025 Preview date: July CY2025 Launched General Availability Preview Worldwide (Standard Multi-Tenant) GCC GCC High Microsoft 365 Microsoft Purview Web
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