Windows 7 repeats a fault in previous Windows operating systems that allows users to mistake executable programs for ordinary text files, thereby compromising their system, a computer security firm has claimed.
On its company blog, F-Secure said Windows 7 repeats the "feature" in previous iterations of Windows that hides extensions for known file types when they are viewed in Explorer.

If virus writers simply rename VIRUS.EXE to VIRUS.TXT.EXE or VIRUS.JPG.EXE, Windows hides the .EXE part of the filename, it said.
"The virus writers also changed the icon inside the executable to look like the icon of a text file or an image, and everybody would be fooled," it said.
F-Secure went on to show screenshots of how Windows 7 repeats this error.
