File types and extensions in email attachments that are common threat vectors
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File types and extensions in email attachments that are common threat vectors


Article ID: 150398


Updated On:


Mail Security for Microsoft Exchange Email Messaging Gateway


 File types and extensions that are common threat vectors in email attachments.


File attachments in email are common threat vectors for malware. Executable files are not the only file type that can include threats. For example, Microsoft Office documents (e.g. doc, docx, xlx, xlsx, ppt, pptx, etc) can contain macros or scripts that include threats.

Blocking specific file extensions or types can limit exposure to risk.

  • Blocking files extensions does not remove all risk of malicious files being received.
  • Blocking file extensions can also block valid files.

Most Symantec Mail Security products have the ability to block attachments by file extension. Some products can also block the true file type, even if the file has been renamed (e.g. foo.exe to foo.txt).

Check your Symantec product documentation to see which file blocking or content filtering options are available.

Note: In cases where users still need to share blocked file types, set up alternative methods to transfer or share these files.

Table: File extensions and types

File Extension

File Type


Access Project (Microsoft)


Executable Application


Active Server Page


BASIC Source Code


Batch Processing


Internet Security Certificate File


Compiled HTML Help


DOS CP/M Command File, Command File for Windows NT


Help file index




Windows Control Panel Extension (Microsoft)


Certificate File


csh Script


DER Encoded X509 Certificate File


Executable File


FoxPro Compiled Source (Microsoft)


Windows Vista gadget


Windows Help File


Project file used to create Windows Help File


Hypertext Application


Information or Setup File


IIS Internet Communications Settings (Microsoft)


IIS Internet Service Provider Settings (Microsoft)


Internet Document Set, Internet Translation


JavaScript Source Code


JScript Encoded Script File


UNIX Shell Script


Windows Shortcut File


Access Module Shortcut (Microsoft)


Access (Microsoft)


Access Diagram Shortcut (Microsoft)


Access Macro Shortcut (Microsoft)


Access Query Shortcut (Microsoft)


Access Report Shortcut (Microsoft)


Access Stored Procedures (Microsoft)


Access Table Shortcut (Microsoft)


Media Attachment Unit


Access View Shortcut (Microsoft)


Access Data Access Page (Microsoft)


Access Add-in (Microsoft), MDA Access 2 Workgroup (Microsoft)


Access Application (Microsoft), MDB Access Database (Microsoft)


Access MDE Database File (Microsoft)


Access Add-in Data (Microsoft)


Access Workgroup Information (Microsoft)


Access Wizard Template (Microsoft)


Microsoft Management Console Snap-in Control File (Microsoft)


Microsoft Shell


Microsoft Shell


Microsoft Shell


Microsoft Shell


Microsoft Shell


Microsoft Shell


Windows Installer File (Microsoft)


Windows Installer Update


Windows SDK Setup Transform Script


Office Profile Settings File


Application virtualized with Microsoft SoftGrid Sequencer


Visual Test (Microsoft)


Windows Program Information File (Microsoft)


Developer Studio Build Log


Windows System File


Program File


MS Exchange Address Book File, Outlook Personal Folder File (Microsoft)


Registration Information/Key for W95/98, Registry Data File


Windows Explorer Command


Windows Screen Saver


Windows Script Component, Foxpro Screen (Microsoft)


Windows Shortcut into a Document


Shell Scrap Object File


Windows PowerShell


Windows PowerShell


Windows PowerShell


Windows PowerShell


Windows PowerShell


Windows PowerShell


Temporary File/Folder


Internet Location


VBScript File or Any VisualBasic Source


VBScript Encoded Script File


Visual Basic project file


VBScript Script File, Visual Basic for Applications Script


Visual Studio .NET Binary-based Macro Project (Microsoft)


Visio Workspace File (Microsoft)


Windows Script File


Windows Script Component


Windows Script File


Windows Script Host Settings File


Exchange Public Folder Shortcut


ADC Audio File


Java class File


Java class File


Microsoft Widows Program Group


Compressed archive file package for Java classes and data


MMS Composer File


ActiveX Control file


Perl script language source code


Silverlight Application Package

Note: This list is by no means exhaustive. It is up to your discretion as an administrator which items to block.