Following are potentially dangerous file extensions in e-mail attachments. That means if you click them and launch them, they will execute instructions in your computer. If a friend sends you an executable attachment in an e-mail and says "this is the coolest thing I've ever seen" or something similar... beware! It could be a virus, and your name could have been stolen from your unsuspecting friend's e-mail address book.

The bottom line is that you must know why you are launching any executable file (see list below). There are countless clever phrases used to trick people into clicking an attachment that wipes out their hard disks. Have you backed up lately? See double extension and extension.

    FILE EXTENSIONS

    Executables (potentially dangerous)
    Know what you are opening!

    .EXE  (machine language)
    .COM  (machine language)
    .VB   (Visual Basic script)
    .VBS  (Visual Basic script)
    .VBE  (Visual Basic script-encoded)
    .CMD  (batch file - Windows)
    .BAT  (batch file - DOS/Windows)
    .WS   (Windows script)
    .WSF  (Windows script)
    .SCR  (screen saver)
    .SHS  (OLE object package)
    .PIF  (shortcut to DOS file plus code)
    .HTA  (hypertext application)
    .JAR  (Java archive)
    .JS   (JavaScript script)
    .JSE  (JScript script)
    .LNK  (shortcut to an executable)


    Text (safe)

    .TXT


    Images (safe)

    Following are common image file types.
    There are many others (see graphics formats).

    .GIF
    .JPG
    .BMP
    .PNG
    .AI
    .WMF
    .TIF
    .EPS
    .PCX
    .DXF


    Data (potential problem)

    .XLS  (Excel) Can contain macros that execute.
    .DOC  (Word) Can contain macros that execute.


    Other Data (safe)

    Data are processed, not executed, and are thus
    theoretically safe.  There are hundreds of data
    file types (see extension).