Free Internet Security Software  Tip Of The Week for 01/04/10

F R E E

By default Windows is set to not show file extensions for most of the known file types. Microsoft felt that this would be less confusing. The text file "letterhome.txt" would just be listed as "letterhome". The problem is that an executable file called "letterhome.txt.exe" would then appear to be called "letterhome.txt" because the .exe suffix would not appear! So if you get an email that contains the file "letterhome.txt" and you click to open it you may actually be initiating an executable file or one of a number of other potentially damaging file types such as a .vbs script. To make sure that the file extensions are shown for most file types do the following:

1. Open Windows Explorer (or any folder window).

2. Select View, Folder Options or Tools, Folder Options (depending on your version).

3. Click the View tab, make sure the option to 'Hide extensions for known file types' is unchecked (the exact wording will vary depending on your version of Windows.

4. Click OK.

Most file types will now show their full name including extension. This hopefully would prevent you from thinking that a dangerous file is safe to open.  A few file types can still manage to hide their true extensions. (A registry edit is required to expose these tricks.) There are other ways to trick you related to file types. One is to put a large number of spaces before the true extension. Another is to intentionally use the wrong extension tag, Windows often will identify the true file type and "help" you by opening it even though it may be a dangerous program. Because of these and many other techniques used to deliver viruses, trojans, worms etc. it is critical to always have a dependable and up to date antivirus program running. Even the most careful individual can at some point be duped into opening a file with a harmful payload and they then are dependent on the capabilities of their antivirus program to protect them. The standard rule should always be followed: Do not open any files that your are not expecting to be sent to you. (Some people open everything that ends up in their inbox and are certainly placing themselves at risk!)