Summary

The default behavior of Microsoft Windows operating systems is to prevent file extensions from being displayed to the user. In addition to making the operating system more user friendly, this behavior also introduces some serious security concerns. However, by following the step-by-step instructions given below, you can choose to make the file extensions visible on your computer.

Step-By-Step Instructions

Windows 7 / Windows Vista

1. Open Folder Options by clicking the Start button, clicking Computer, clicking Organize and then, clicking Folder and search options.
2. Click the View tab and then, under Advanced Settings, do one of the following:
   • To show file name extensions, clear the Hide extensions for known file types check box.
   • To hide file name extensions, place a checkmark for Hide extensions for known file types check box.
3. Click OK to save your new settings.

Windows XP / Windows 2000 / Windows 98 / Windows 95

1. Open Control Panel by clicking the Start button, clicking Settings and then, clicking Control Panel.
2. Depending on your operating system, do one of the following:
   • Windows XP / Windows 2000: Click the Tools menu and then, click Folder options.
   • Windows 98 / Windows 95: Click the View menu and then, click Options....
3. Click the View tab and then, under Advanced Settings, do one of the following:
   • To show file name extensions, clear the Hide extensions for known file types check box.
   • To hide file name extensions, place a checkmark for Hide extensions for known file types check box.
4. Click OK to save your new settings.

Why is it such a big deal?

Let's say you have a file "myfile.doc" on your computer. If Windows is running with its default behaviour of not showing file extensions, then you will see only "myfile" instead of "myfile.doc".

Malicious softwares exploit this fact and trick users into opening a file that appears to be something it is not. For example, a file named "my_nude_picture.jpg.exe" would be displayed in Windows as "my_nude_picture.jpg".

Because the file extension in this case is .exe, it would not be displayed and the file would seem like a .jpg file. Without even realizing this fact, a user might get lured into opening the file and therefore, getting his/her computer infected with viruses, or spyware, etc.

External Links

1. Exploitation of Hidden File Extensions