Blocked file types in SharePoint 2010

Each Web application maintains a list of blocked file types that is based on file name extensions. For example, you can block files that have the .exe extension because those files can be run on the client computer and can contain malicious code.

By default, many file types are blocked, including file types that are treated as executable by Internet Explorer. Files, whose names include braces, (for example, filename.{doc}) are also blocked by default.

Following are the file types that are blocked by default and their corresponding file name extensions.

.ade	Microsoft Access project extension
.adp	Microsoft Access project
.app	Application file
.asa	ASP declarations file
.ashx	ASP.NET Web handler file.
.asmx	ASP.NET Web Services source file
.asp	Active Server Pages
.bas	Microsoft Visual Basic class module
.bat	Batch file
.cdx	Compound index
.cer	Certificate file
.chm	Compiled HTML Help file
.class	Java class file
.cmd	Microsoft Windows NT command script
.com	Microsoft MS-DOS program
.config	Configuration file
.cpl	Control Panel extension
.crt	Security certificate
.csh	Script file
.dll	Windows dynamic-link library
.exe	Program
.fxp	Microsoft Visual FoxPro compiled program
.hlp	Help file
.hta	HTML program
.htr	Script file
.htw	HTML document
.ida	Internet Information Services file
.idc	Internet database connector file
.idq	Internet data query file
.ins	Internet Naming Service
.isp	Internet Communication settings
.its	Internet Document Set file
.jse	JScript Encoded script file
.ksh	Korn Shell script file
.lnk	Shortcut
.mad	Shortcut
.maf	Shortcut
.mag	Shortcut
.mam	Shortcut
.maq	Shortcut
.mar	Shortcut
.mas	Microsoft Access stored procedure
.mat	Shortcut
.mau	Shortcut
.mav	Shortcut
.maw	Shortcut
.mda	Microsoft Access add-in program
.mdb	Microsoft Access program
.mde	Microsoft Access MDE database
.mdt	Microsoft Access data file
.mdw	Microsoft Access workgroup
.mdz	Microsoft Access wizard program
.msc	Microsoft Common Console document
.msh	Microsoft Agent script helper
.msh1	Microsoft Agent script helper
.msh1xml	Microsoft Agent script helper
.msh2	Microsoft Agent script helper
.msh2xml	Microsoft Agent script helper
.mshxml	Microsoft Agent script helper
.msi	Microsoft Windows Installer package
.msp	Windows Installer patch package file
.mst	Visual Test source files
.ops	Microsoft Office profile settings file
.pcd	Photo CD image or Microsoft Visual Test compiled script
.pif	Shortcut to MS-DOS program
.prf	System file
.prg	Program source file
.printer	Printer file
.pst	Microsoft Outlook personal folder file
.reg	Registration entries
.rem	ACT! database maintenance file
.scf	Windows Explorer command file
.scr	Screen saver
.sct	Script file
.shb	Windows shortcut
.shs	Shell Scrap object
.shtm	HTML file that contains server-side directives
.shtml	HTML file that contains server-side directives
.soap	Simple Object Access Protocol file
.stm	HTML file that contains server-side directives
.url	Uniform Resource Locator (Internet shortcut)
.vb	Microsoft Visual Basic Scripting Edition file
.vbe	VBScript Encoded Script file
.vbs	VBScript file
.ws	Windows Script file
.wsc	Windows Script Component
.wsf	Windows Script file
.wsh	Windows Script Host settings file

Reference: http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.administration.spwebapplication.blockedfileextensions.aspx

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